Unless there is a new model I’m not aware of I think you may be asking about a Delta 3 FDX10.
I’ll break it down for you a bit. The FDX10 is the present top of the line first stage of the oceanic line that is used with the present top of the line second stage the EOS. It is a well tested performer that is considered oe of the best cold water performers. The second stage you named the Delta 3 is a older model that was once the top of the line second stage. It is a top notch breather. As I noted it is a older model and was replaced by the Delta 4 which is what I presently use. Even the Delta 4 has seen a model change to the Delta 4.1 which saw a change of the purge cover and a removal of the swivel hose. The present incarnation is the Delta 4.2.