Do all wallets use specific explorers? If so, is there a way to identify which explorer the wallet is using? Most of the major-mid tier wallets seem very ambiguous or don't seem to mention this at all.
Given the tags you're setting on your question, I believe you're confusing currencies, wallets, and explorers.
Bitcoin (BTC) and Bitcoin Cash (BCH) are currencies with an associated blockchain.
Wallet/node software is what you use to interact with that currency.
- Software that interacts with BTC includes Bitcoin Core, Bitcoin Knots, btcd, Electrum, Greenbits, ...
- Software that interacts with BCH includes Bitcoin ABC, BUCash, Electron Cash, ...
Explorers are independently run websites that visualize information in particular blockchains. They are unrelated to wallets, and generally something you should avoid for anything but debugging purposes. Relying on a specific website as your source of truth is dangerous as the website may lie. Wallet software generally performs some level of local validation of transactions (or even full validation, meaning that no invalid transactions will ever be accepted). Some explorers have associated wallet software, which relies on that website for information, rather than directly connecting to the network. These are generally discouraged for the same reason.