How is the WTC project different from ARK or OMG?
Ark is is a platform for Dapps, comparable to something like Lisk/Ethereum/etc
OMG (at a high level) is like a universal wallet that's basically trying to act as a bank for people that don't use banks
WTC is focused on supply chain logistics using RFID technology.
They don't really overlap much at all.
What do you mean by its own chain?
Ethereum is usually the blockchain of choice for token sales/ICOs for companies that don't have a their own blockchain but plan to have one down the line. Whenever this applies, that means the token is temporarily on Ethereum blockchain. This also means that if you own the tokens prior to the chain switch, you will need to follow up on the process to swap your tokens to the new cryptocurrency native to the new blockchain. Qtum is a good cryptocurrency to track if you want to see a recent case of how this whole process unfolds as they've just completed a blockchain switch.