Considering both are "unlocked" SKUs, I'd say to get the Ry3600 under one big assumption: it has the same cooling solution OR you're using your own aftermarket cooling one.
As for the performance out of the box, I think the TDP is just a reflection of the clocks behaviour under big loads, so it would have a lower all-core speed and less thermal headroom overall (assuming lesser binned part).
I'd love to read more reviews of those 2 in order to have a better understanding of them, but I haven't found many. What I've found though tells me they're really close to each other. Much like the Ry1600 was to the Ry1600X.
Cheers!