Just as the title states, how can you tell them apart?

 

if those are the only two your comparing , FD housing exhaust port has no diffuser, s5 na has diffuser

 

the FD housing will have a small groove on the "legs" to hold sealant

 

Thanks for your responce guys, I forgot to mention, I knew about the difference in diffusers.
j9fd3s I'm not familiar with "legs", could you clearify? Any other differences?

The reason that I'm asking is that I'm getting an S5 Turbo engine with one bad housing rebuilt , and I can get a hold of an FD housing to swap it in, just want to know if it's going to work. I know the FD housing doesn't have the coolant passage like the S5 Turbo housings, and it looks like a S5 NA housing. Thanks in advance for your responce.

 

http://www.pineappleracing.com/13b-r...usingrear.aspx

see the little cut near the bottom? from the oil pan up?