AWS as far as I know does not promise a specific "public" speed, they only give you the speed of the local network interface (for some instances just in vague terms, not as a number), and the internet connection is somewhere below that. The internet access is also an extra component there, e.g. you connect a gateway to your instances local network.
Your typical VPS provider setup doesn't work that way, so it's not very surprising they just apply one speed limit to the interface, which is geared towards public traffic limits, whereas with AWS the interface limit is geared towards internal traffic and the external limit set elsewhere. With some VPS providers you can get an internal network as an extra.
