What's the difference between all three of these sprays besides a mild flavor
Difference. The nutrition facts list no fat, saturated fat, sodium, protein, etc.

Well... the difference is the source of the oil.

Canola oil (from Canadian Oil, Low Acid) is from rapeseed

Olive oil is from... well... you know.

Butter spray... is butter, in a can.

https://www.askmehelpdesk.com/food-drink/healthiest-oil-kitchen-199890.html?highlight=canola

Fats 101: How to tell Good Fats and Bad Fats (http://www.healthcastle.com/goodfats-badfats.shtml)

The best oils are the ones found around the olive oil. The worst ones are with the Crisco/Wesson oils.