Both pilot watches and both with blue dials. Some evident pointers:
Bremont is more rugged: hard case+100m WR
IWC is more classy and Iconic
Bremont has the day in addition to the date
Bremont has the inner bezel that you can use to measure elapsed time
IWC is a limited edition and a better recognized brand
Retail price is about the same
IWC Mark XVII "Little Prince"
Bremont U2 blue dial
I would say that if you want a dressier choice then IWC but if you want the rugged and functional go for the Bremont. I feel that once you bypass the brand name the choice is harder.