Question about head on a beer

[Mesa512]

What exactly determines how thick the head will be on a beer. For example I crack open a Sam Adams and it has a decent head, then I pour myself a boddington cream ale and the head is huge. What causes the difference? Thanks

 

[SumnerH]

What exactly determines how thick the head will be on a beer. For example I crack open a Sam Adams and it has a decent head, then I pour myself a boddington cream ale and the head is huge. What causes the difference? Thanks

Boddington's out of the pint can? That uses a nitrogen widget, which gets you a big thick creamy head that hangs around. It's the same thing Guinness draught cans/bottles (but not Guinness extra stout bottles) use.