Europe, which is not a special kind of dollar, refers to dollars deposited in banks outside the United States and not regulated by the Federal Reserve System, which are homogeneous to the dollars circulating within the United States, having the same liquidity and purchasing power.
The difference is that Eurodollar is not regulated by financial institutions in the United States and is not subject to relevant banking regulations and structures.
Eurodollars are held as dollar deposits at foreign banks outside the United States, mainly at European and European branches of U.S. banks, or as dollar loans borrowed from those banks.
Eurodollars are the same and have the same value as U.S. dollars in circulation. The only difference is the way they are handled financially.
