As for Sicilian Defense, 1. ...c5 by black makes the game non symmetric. That is just the start of the story. In many variations of the Sicilian you get opposite side castling (not always) and aggressive play by both sides. Some openings like the exchange French gives you a symmetric position that is drawish on higher levels. Note that on lower levels all of this isn't that important because games are very likely to be decided by basic tactical shot or straight up blunder.
Anyway, on your level you shouldn't focus too much on the openings you play (if you wish to improve optimally). The thing is, memorizing without understanding will not really do you much good, and in many cases your opponents will not play main lines. When they play some sideline you will not know how to respond because you were only memorize the opening without understanding it.
You should pick some mainstream variation, and build up on it slowly. Focus on the opening principles , develop your pieces and all that jazz. Here is what you need to know about the opening for now:
https://www.chess.com/blog/nklristic/surviving-the-opening-first-steps-to-chess-improvement
If you need anything else, feel free to ask. Welcome to the site, I hope you will have a great time here.
Openings


Chess Openings Resources for Beginners and Beyond...
https://www.chess.com/blog/RussBell/openings-resources-for-beginners-and-beyond
https://www.chess.com/blog/RussBell
Hi! I'm new to chess.com, and i am interested in some of the openings. I mostly use caro-kann and french. Do you have any ideas for openings from 700-900 elo? Also can someone explain me why would you play the sicilian defense?