So my question is will this create giant forks and if so, how will it be determined which one is "Bitcoin" and which ones are not?
So far its quite puzzling to me. Thanks.
With Classic possible fork, it could happen 28 days after 750/1000 blocks signed as BIP102.
I said it "could" because miners aren't forced to make bigger blocks, anyway after these 28 days Classic nodes will start accepting bigger blocks.
Bitcoin then (after the possible fork) will be the chain with more work.