Are Hashed Timelock Contracts and Zero-Knowledge Contingent Payments the same thing?
Not really. Both use OP_CLTV, in order to recover from a situation where one side refuses to participate in the protocol, but other than that, they're pretty different.

ZKCP has a zero knowledge proof communicated outside of the blockchain. On the other hand, HTLC passes signed transactions back and forth to update a channel.