Dragon Ball (non-canon)

Dragon Ball being such a popular franchise has several spin-off material that deviates from the original canonicity of the serie, here are the examples.

Anime Filler
Dragon Ball anime had plenty of filler so that the manga could advance and they had enough chapters to make the next anime episodes out of. Filler was mostly inconsistant and should be ignored if it contradicts the original storyline.

GT
The pinnacle of filler, an entire spin-off serie supposedly happening several years after DBZ. It tried to combine the adventurous aspect of DB with the fighting of DBZ, but mostly failed and like all the filler made incredible inconsistencies which often made the series portrayed power level to be downplayed.

Movies
The movies and OVA's are totally side-stories which do not fit in the slightest with the original storyline and should thus be taken with a grain of salt. Considerably entertaining introducing some decent villains like Broly, Janemba and Hirudegarn, however the movies introduced one of the biggest wanks in DBZ: Broly being a galaxy buster. This is disproved even in the actual movie, but most biased people tend to ignore it and try to apply the non-existant feat to characters from the original storyline (?).

Only canon OVA would be Yo! Son Goku and his friends return (written by a friend of Akira Toriyama under his permission and mentioned in Battle of Gods) and Battle of Gods, which is a continuation to the original storyline written by Akira Toriyama and actually expands the DB-verse we knew.

Others
There are several other spin-off media derived from the DB franchise, but just like mentioned above it is all non-canon.

Power Levels
Ignoring the inconsistencies, the part of the franchise that isnt part of the main canon tends to be a bit stronger, showcasing some clear MFTL feats with there blasts and universal destruction via chain reaction. In head on battle however, they seem to be somewhat inferior to the original serie due to the recent reveal of the dimension of power of the higher gods in the Battle of Gods movie.