outsourcing vs on network translation

I could use some help understanding the differences between edi
outsourcing and on network translation.

I have been asked to look at outsourcing our EDI functions and have
talked with several providers. I have seen a wide variation in
pricing and it seems that on the low end is on network translation and
the high end is EDI outsourcing. But the vendors who offer on network
translation are saying that their service is very similar to
outsourcing and they will provide "everything" we need.

Does anyone have experience differentiating these services?

What do you get with one that you do not get with the other.

Thanks,

Jerry