After studying and analyzing data from packet captures of both scans I discovered the answer. Apparently, OpenVAS works this way:
1) TCP 3way handshake on port
2) OpenVAS asks different famous protocol questions (HTTP, telnet, etc.) to get an answer with data (banners).
3) If it does get answers, it will create a report with all that data and say its open.
3)If it does not get an answer for them, OpenVAS will say its closed as he cannot give further data about the service the port is running.
So, what happened with ports 27000, 49154, 50095? These ports have very rare services running therefore OpenVAS did not ask questions for those specific and not usual protocols. As a result OpenVAS did not get answers and gave those ports as closed.
On the other hand Nmap just needs a succesful 3way handshake to give a port as open and like OpenVAS, Nmap did get 3way handshake for all those ports and did not try to get further data.
I hope I explained myself well enough. Thank you all for your help and advice.