Both Bell fibre and OTA use mpeg2. Flipping between Bell and OTA I cannnot tell the difference. Both satellite providers produce an inferior signal because they have to use added compression ( sometimes mpeg4) as all their channels have to be broadcast simultaneously from their satellites. The fibre TV signals are sent out over fiber optic to the OPI (those brown Bell boxes by the side of the road ). Fibre then sends out only requested channels to receivers in the house over dedicated wires. This uses much less bandwidth. Rogers also uses fiber optic to their OPI (green boxes by the side of the road). From there the signal uses a common coaxial cable to all the houses.
OTA has the advantages of being free and with added channels. Bell and Shaw satellite use different compression algorithms producing noticeable differences.