I've got brown rot but is it dry rot?

[Gandalf the Inept]

Our windowframes have been neglected for a long time and have rotted right through. Lots of filler and bodgery, not so much keeping the water out. There's a timber running underneath the window which has completely rotted out, and there's damage to the vertical timbers supporting it too. It's really darkened the previously reddish pine. Definitely brown rot but the million-dollar question is - is it dry rot? How would I tell the difference? It does appear to be limited to timbers that have previously been wet, which is encouraging, but I don't want to conclude things are OK too fast in case I'm wrong!

I hope you don't mind me appearing as a first-time poster and asking for advice. Also, apologies for the large picture size! Any thoughts would be gratefully received.