Position matters in poker. The player with the dealer chip in front of them will always have an advantage throughout the entirety of a hand because they are last to act. As a result, they can play more hands.

This website shows which hands to play before the flop in no-limit texas holdem based on the position you are sitting in and what other players do.

The order of betting in a 9 handed poker game pre-flop is as follows:
1. under the gun, utg
2. utg+1
3. utg+2
4. lowjack, lj
5. hijack, hj
6. cutoff, co
7. button, btn (a reference to the physical dealer chip)
8. small blind, sb
9. big blind, bb