Blocknets main exchange is Bittrex, but due to US laws, citizens from the US aren't allowed to trade on Bittrex, which makes BLOCK incredibly hard to buy for anyone residing in the US.
The team decided to make their own ERC20 token of BLOCK, and make it tradeable on Uniswap.
1 aBlock = 1 BLOCK.
Blocknet is a pretty interesting project which allows you to run your own node on their DEX and profit off of trading fees. Their nodes will also be part of their oracle network, so while the Bullrun will push coins to the sky, Blocknet node owners will profit passively from all the action, which is pretty damn cool