Nottingham vs Muntons

OK, this NOT another "is my fermentation stuck" thread. I am just curious about how different these two brands of dry yeast are. Here is some info. For several times I have brewed a mini-mash kit of AHS Ordinary Bitter Ale (aka "lawnmower's ale"), and it turned out great. I played with maltodextrin, changed LME/grain ratio, fermented at different temperatures - it was always good. The original recipe calls for Muntons Premium Gold dry yeast. Usually it started bubbling in about 4 hours at 72 (+/-2) degrees. Now I am away from Austin, and bought all the ingredients in a local store (Alpharetta, GA). They did not have Muntons yeast, and so I had to buy a package of Nottingham (Danstar) dry ale yeast. Also, my only thermometer died during the move, so I might have pitched at a slightly higher (but not too much!) temperature than usual. It began bubbling after 8 hours, and keeps doing so at a steady rate of 1 bubble per minute for the past 48 hours. Can this difference be connected with the brand of yeast? Or does it have anything to do this: I finally switched to a full boil and had ~7 gallons in the pot as opposed to 3.5 that I boiled before. Any ideas are welcome. Thanks!