The EPS helmet is going to fit and look almost identical to to the Brock Hard hat, it will be a bit warmer since the EPS does not vent as well as the brock foam does.
The main difference is that the EPS is a helmet, the brock is not, it is a hard hat. The helmet (EPS) is designed to absorb an impact by shattering or cracking (instead of your skull). It is only good for one impact affter that it needs to be replaced.
The Brock Hard hats are not helmets, rather they are hard things that go on your head and can absorb smaller impacts multiple times. Affter an impact the Hard hat will not necesarily need to be replaced, it won't however provide as much protection as a helmet will.