One work stream.
Two networks.

A participating Zcash pool can include a Wcash commitment in its Equihash job. The same work stream can then produce results valid for Zcash, Wcash, both, or neither, depending on each network's target. A Wcash-qualified result carries an auxiliary proof to Wcash.

What stays separate

Wcash validates its own blocks and has its own difficulty, state, issuance, and transaction history. WEC and ZEC are different coins on different networks. Wcash's fixed-term development rule directs 30% of newly issued WEC subsidy to the Foundation from block 33,000 through 621,454; miners receive the remaining 70% plus all fees. It does not take any part of ZEC rewards.

Participation is explicit. Zcash hashpower does not automatically secure Wcash; a pool must support the Wcash commitment and payout path. ZecWec is one merged-mining pool associated with the project. Molepool is an independent third-party pool.

Why the integration work matters

Reuse of work reduces the additional mining effort for participants, but it does not remove the need for pool software, payout accounting, monitoring, operator instructions, or consensus review. Those systems have to be maintained as both networks evolve.