Practical differences between 1. e4 and 1. d4 ?

"1 e4 best by test" - Fischer
"1 d4 dull & drawish" - Fischer

Ohhhh if you think that 1. d4 openings do not have traps, you should play 1. d4 against me

You might think of 1.e4 is open while 1.d4 is closed.

Here's a sample of 1.e4 closed:

And here's a sample of 1.d4 open:

Fischer literally admitted in his later years that 1d4 was probably better.

Source: https://chess24.com/en/read/news/boris-spassky-i-m-waging-a-war

" are there any fundamental differences between e4 and d4 openings in terms of resultant games?" yes. e4 is unsupported on move one. and it is necessary to develop another pawn or piece to do so. d4 is already supported by the Queen which allows more freedom of development. example, 1.e4,Nf6 and the pawn will have to be advanced or protected. 1.d4,Nc6 and white can play c4, or any other move without loss of the pawn or the need to advance it. nearly all e4 openings deal in some way with how white chooses to deal with an attack on e4.