"I'm thinking of positions where one side has a range of decent and intuitive moves to choose from while the other will need to string together a number of only moves just to survive."
Wafflemaster, it is hard to imagine what equal position is actually like this 
. The only thing I can think of is a combination that ends up in an equal position but if you miscalculate the combination you lose a piece or something.
@ elubas
Well, I'm starting to see your point actually. I'll have to think about what I mean by all of this. Maybe there's a lot more preference to it than I thought.
I think I mean moves that are intuitive to me make a position easier to play. How intuitive they are to the chess population in general is not easy to define. Skill level, experience, and what they've bothered to learn makes it at least a little different for everyone.
I think most basic considerations like outposts, open files, secure king, passed pawns, etc are intutive considerations, but there are so many exceptions, even well known exceptions that again it's probably too hard to say for sure. So you probably can easily fault the annotator 
So, it seems we have two opinions:
1. Theoretical = objective
2. Objective = practical (not theoretical)
Still confused. The "theoretical" assessment does not derive from opening theory, by any chance?
Therotically, the fried liver is better for black--white's sacrifice is unsound. Practically, few are brave/foolish enough to play it for black, as white scores something like 70% in actual games.
Could this be a good example of what we're trying to say?
Positions should be given evaluations and standard deviations, the latter to
indicate the uncertainty and risk involved.
"Objectively" and "Theoretically," are generally used synonymously, for better or worse, when referring to a chess advantage. It's talking about who is better not in practical terms, so not considering how easy a position is to play.
Personally, I often don't buy it when people say "it's equal, but easier for side x to play." Maybe if you have a certain style of play, but if a position is truly equal, either neither side is under a lot of pressure, or one side is under more pressure but there is a compensating factor (like material) -- so comfort level of each position should be even too. So it totally depends on the playing style of the individual, which varies a lot.
In the smith morra example, I would say the fact that black's center pawns block out some of the white activity, and the fact that he can give up a pawn to relieve the pressure without being down in material, and the fact that his position tends to get better the longer the game goes, make black's position at least as pleasant as white's, assuming a universal style.
If of course one side prefers to attack rather than to consolidate, then they may prefer to play white. At the same time, some players may enjoy the gradual process of consolidation, and would prefer to play as black. I argue that "ease to play" is very relative -- you can't say absolutely that one side is easier to play.
I love positions which are theoretical drawn, but you can just nurse it, and eventual the opponent makes a mistake, and I gain a slight edge. Then nurse it to the win. Thats a consolidation. But I play the SMG to learn these sharp games. To learn a new side of chess. But in blitz I still have great results (around 70% as white), while in Ruy Lopez, which often gives the position I just love to play, have a mere score of around 51%. I will then say the position is easier to play as white, but should theoretically give a slight black edge.
"For example, where passive defense is required, this is often very difficult to play. It's a factor of human nature - there is no chess style where a player prefers passive defense."
I don't think you can know this. Passive defense is just a certain type of logic -- I don't think it is physically impossible for someone to come along and appreciate it.
Also, again -- how many equal positions do you know where one side is passively defending?
It's interesting to think about what we consider "theoretically slightly better," too. Because in reality, what we call a "slight advantage," a perfect chess player would say that there is no advantage at all, because he knows no matter what side he takes, the result will be exactly the same against another perfect player (draw), and so he couldn't prefer either side.
I think what we call an objective advantage has something to do with which side is putting on more pressure in the first place! If white is attacking a pawn, black is defending it, everything else being equal, we often say "white has a pleasant edge." Yet, two perfect chess players playing each other could care less -- they would certainly not fight over who gets to play white. So it could be argued what we call "objective non-winning advantage for white" is really more like saying "The position is equal, but white's position is easier to play."
So I think that we embody the idea of a side having to come up with defensive resources already when we say one side is "better" or "worse" -- if this is the case with an "equal" position, you have to wonder why it didn't make the qualifications for an "objectively slight" advantage.
It isn't even possible to say that "equal" positions are exactly equal - unless it's a known theoretical drawn ending from the tablebases.
But I do think it is possible to have a roughly even position which is easier for one side to play. For example, where passive defense is required, this is often very difficult to play. It's a factor of human nature - there is no chess style where a player prefers passive defense.
That said, if an annotator says such a thing, he ought elaborate on why he believes if. His job is (theoretically) to illuminate, not obfuscate.
Au contraire- the annotator must keep the reader in baffled awe lest the ignorance of the former be revealed to the latter!
When I think of a positions that are harder for one side than the other I'm thinking of positions where one side has a range of decent and intuitive moves to choose from while the other will need to string together a number of only moves just to survive.
But again, preference and temperment come into play. A player who is a poor strategist but a tactical wizard might find it easier to find and play a series of "only" moves than to judge between several alternatives, all of which look superficially playable.
Hmm, that's a good point.
I try to change it up in my previous post. How about "number and non-intuitive-ness of moves necessary to maintain the evaluation"