Ravenmyste wrote...
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Edmonton is the main studio, where Bioware is traditionally based. They handled most of the SP campaign as far as we know, and as far as I know all of the writers are based there.
Montreal is a newer studio, it helped Edmonton with ME3 (most obviously with most of the MP and some of the DLC). Mike Gamble has been hinting for months that Montreal is also working on other things, which could've included Leviathan, this DLC, more MP DLC... etc. The goal for Montreal is for it to grow enough to handle whole projects by itself, but it seems to have a lot of artists and gameplay people.
Basically, both might do different things at different times, but they also work together. It's not like one exclusively handles all MP content, and one does SP. They're two parts of a bigger Bioware studio that is working on ME3.