If it's bagseed, even if you get your stuff from the same guy, it could very easily be different strains.
I sprouted 3 seeds, got lucky and they were all ladies, but had one Indica dominant, one Sativa dominant, and one looked 50/50.
They all 3 grew at different speeds from seed until now.
Note: I couldn't even tell the diff. in leaves for a month or so.