On that line, Spezza played off the wall a lot more.
Only on the PP.
Alfie's trademark zone entry was to bring it in on the wing, then do a stop and curl back, looking for a passing option in the centre, or create enough separation to go on net and shoot. The opposition never really knew when he'd do it, so it was a fairly reliable and efficient way to buy a little time and space. He was surprisingly difficult to knock off the puck with his big shoulders, and he didn't mind fishing pucks out of the corners.
Spezza would usually come in down the centre, looking for either the drop pass (which Ottawa fans would rapidly tire of sometimes) or Heatley's stick high in the air on the wing for the one-timer.
Heatley would be on the wing, but his real knack was knowing when and where to go around the net. He always seemed to be in the right place at the right time and he didn't miss on rebounds or open nets very often.
Spezza didn't spend a lot of time on the boards or in the corners, so I'm not sure I agree with that characterization.
On the PP, Spezza spent a lot of time on the half-boards, but that's a pretty standard position for a playmaker.
Personally, I think Alfredsson was the better player over Bergeron. He was better offensively IMO and he was no slouch defensively himself.
Seasons with 70+ points:
Alfredsson 103
Alfredsson 89
Alfredsson 87
Alfredsson 80
Bergeron 79
Alfredsson 78
Alfredsson 74
Bergeron 73
Alfredsson 71
Alfredsson 71
Alfredsson 70
Bergeron 70
Keep in mind, Bergeron's first season was in 2003-2004 so he missed virtually all of the dead puck era.
5 of Alfredsson's 70+ seasons occurred when NHL scoring was at its lowest.