it was already said EA's got the better graphics. no question there.
although IMO, espn's make the game seem more realistic.
but compare the 2 with actual gamesplay camera angles.

thats where it matters to me. i couldnt care less about replays.
when you get into the actual game tho, graphics mean so little. EA is a high scoring arcade style, which goals can get up into the 20's. EA hockey games always have the one way that seems to always score. This year its thier new wrap around goal. EGM already says it scores at least 50% of the time. which is just unacceptable.
ESPN is a much much more simulation style where much of the time goals stay below 4
EA is holding itself up in the hockey game community by reputation. people dont want to let go of the brand name they've held for so many years. ESPN is bulding a reputation on solid gameplay
one of the main things for me tho is the online stuff. EA has tournaments and head to head gameplay online only.
ESPN's will have all that plus leagues and party mode.

leagues are great fun online. its like playing a season with real people.
and i wrote the release dates in the first post;
EA - 9.14 for PS2 // 9.20 for Xbox
ESPN - 8.30 for both PS2 and Xbox