Permanent resident vs US citizen - getting a mortgage.

[Daniel Madsen]

So, I've gotten super excited about real estate these past couple of months, specifically multi family. Because of this, I got super bummed out when I heard the fact that it's a lot more difficult AND expensive to get financing for US property if I'm not in the US. 

You see, I'm from Denmark. However, I'm super excited about US real estate and I'm actually pretty sure I'll be moving to the US to live. 

I researched US citizenship and I found that I have to be a permanent resident for at least 5 years before I can become a US citizen. I cannot wait that long to buy real estate.

I don't think becoming a permanent resident would be a problem, though.

So, here's my actual question:
When people say it's cheaper to get a US mortgage if I'm in the US, are they talking about residence or citizenship? 
If I want the same US mortgage deals that you guys can get, is it enough for me to become a permanent resident, holding a green card, or do I have to be a US citizen?

Thank you so much in advance!