A comparison i that dont think has been posted.
Unless you have good language skills its just a picture job :D
Gear for Image :: Sigma 150-600mm f5-6.3 C vs Tamron 150-600mm f5-6.3 VC @600mm
Doing a bit of a search on this as i enjoy the challenge of finding things,your question had already made the search results so i clicked it for fun and got this :D
This may turn into a double learning thread as i am now learning the full photoshop,this was an image i took with my 70-300,decided to see how much it would crop now i have extra tools to play with.
Still loads i could have done but it is a learning curve.
Just had my second problem,did some work in ACR then clicked to open in photoshop, got this result,i closed it down re did the ACR and it moved into photoshop again no problem this time,any idea what happened to the first one to end up like this.