What is the difference between a US embassy vs. consulate and what determines which foreign nations get one or the other?

I was listening to an interview with Col. Bill Cowen this morning and he pointed out that it was a consulate rather than an embassy in Benghazi. And that an embassy is better staffed and hardened security-wise than a consulate thus making Benghazi more vulnerable.

I’m assuming his info is correct so that has me wondering my two questions above.

It just seems to me that the US presence in a dangerous area should warrant the full protection and security provided by an embassy while more peaceful countries (Scandinavian countries, Ireland, etc.) could get by with less defensive protections in place so a consulate could get the job done quite adequately.

But what do I know about defensive necessities in hostile nations? Hence my Qs.