Its the same as far as i know. But i think that Ams 2 allows private networking.
Have a look at this blog post - https://www.digitalocean.com/blog_posts/digitalocean-announces-second-amsterdam-datacenter-ams2

Hello!

To add to cameron's information - AMS1 and AMS2 are different facilities with different networks.

They use the same type of technology, with the exception of AMS2 having additional equipment to support private networking.