Is There a Difference Between Old and Middle Irish?

The most prolific and voluminous a vernacular literature of any western european mediaeval culture. The sources that i i'm talking about are written in the vernacular, in either old or middle irish. A lot of them are also written in latin, so i'm dealing with latin sources as well. And one of the things i was trying to do is demonstrate the sheer variety of sources that are preserved from mediaeval ireland. I mean, and to be honesti's there's so much of it that quite a few significant sources have never even been published or translated into english.