Both Laco and Stowa were manufacturers of the original flieger watches for the Luftwaffe. In this, they obviously both have the same history and heritage.
As far as the watches go, Stowa are more refined. The steel is a quality brushed finish on the Stowa, they use decorated ETA movements and are more expensive as a result.
Laco used to use the basic Miyota movement, although I think they use ETA in some models now, they have a more agricultural, blasted finish, but are cheaper.
I've had both and while the Stowa was a lovely watch, the Laco somehow felt more authentic, like the tool watch it was originally designed to be.
Hope this helps