What does "不等“ add in 从A到B不等?
I would say the meaning is the same.

'从 ... 到 ...' is a phrase to describe a range, while '不等' means 'diverging'. Putting '不等' at the end will to some extent emphasize the meaning of 'diverging within a range' and you can take it as an echo for the phrase which makes the sentence more complete and sounds better.