Hi...
In answer to your question, if you check this website
www.stormbirds.com and select the 'Me262 project' tab, and click through to page 3:
Aircraft profiles - configuration data, it states that all operational wartime Me262s were suffix 'a' models, with Jumo 004 engines, and all experimental models were 'b'-suffixed, indicating BMW003 engines and therefore, the modern replicas but in the USA are following on with 'c'-suffixed machines, denoting the use of the modern J-85 jet engines used in the replicas.
An interesting site, although in my ignorance, I have no idea if the 'suffix-to-engine type' designation is accurate. I dare say someone more acquainted with the originals machine would be able to inform us.
Regards...
Paul