- **Bitcoin Multisig**: In Bitcoin, multisig is natively supported at the protocol level using a specific type of script (P2SH or P2WSH). Bitcoin’s Script language allows multisig directly by requiring multiple private keys to sign a transaction before it can be broadcast and confirmed. This approach is efficient and secure, as it doesn’t rely on external contract code, and Bitcoin nodes can validate multisig transactions natively.
- **Ethereum Multisig**: Ethereum’s multisig functionality is implemented via smart contracts, as Ethereum’s protocol does not natively support multisig. A multisig contract on Ethereum defines the rules for the required signatures and tracks approvals, only executing a transaction once the specified number of signers has approved it. Since it’s contract-based, multisig on Ethereum can support more complex conditions and flexibility but requires custom code and higher gas costs.

- **Bitcoin**: Bitcoin multisig is inherently secure as it’s part of the core protocol, minimizing risks associated with bugs in custom code. As long as the Bitcoin Script works as intended, the multisig is highly reliable. Additionally, multisig transactions are deterministic, meaning Bitcoin nodes don’t rely on additional code beyond Bitcoin’s standard transaction processing.
- **Ethereum**: Since Ethereum multisig depends on smart contracts, its security is highly dependent on the code quality and thoroughness of security audits. Custom contracts can introduce vulnerabilities, as seen with bugs in past Ethereum multisig implementations (e.g., Parity Multisig hack in 2017). While Ethereum contracts are flexible, this reliance on external code makes Ethereum multisig potentially less secure than Bitcoin’s built-in solution.

- **Bitcoin**: Bitcoin’s multisig options are relatively straightforward, typically limited to “m-of-n” schemes (e.g., 2-of-3 or 3-of-5) where a set number of signers are needed. This straightforwardness aligns with Bitcoin’s focus on simplicity, security, and minimizing the risk of unexpected behavior.
- **Ethereum**: Ethereum multisig contracts, like Gnosis Safe, can support complex authorization rules, such as role-based permissions, transaction limits, time delays, and conditional logic. This flexibility is a significant advantage for more complex use cases, like DAOs or multi-user wallets, where customization is essential.

- **Bitcoin**: Bitcoin’s multisig transactions are typically cheaper because they only require the transaction data and signatures, without the overhead of executing smart contract code. However, they are slightly larger in size than regular Bitcoin transactions, so they incur slightly higher transaction fees.
- **Ethereum**: Multisig on Ethereum requires deploying and executing smart contract code, which consumes gas. Since each multisig transaction calls the contract’s code and may require multiple signatures, it can be significantly more expensive than standard Ethereum transactions, especially when network gas prices are high.

- **Bitcoin**: Native multisig setups are used for many Bitcoin wallets, including enterprise-grade wallets like BitGo and Casa. These services often use m-of-n multisig structures for added security.
- **Ethereum**: Gnosis Safe is the most popular multisig solution on Ethereum, offering a highly flexible, customizable multisig wallet that integrates well with decentralized finance (DeFi) and DAO applications.

- **Bitcoin**: Bitcoin’s multisig transactions are identifiable on the blockchain due to their unique structure (e.g., P2SH or P2WSH). However, the specifics of the multisig setup (like the number of signers) aren’t visible on-chain.
- **Ethereum**: Because Ethereum multisig uses smart contracts, all details of the multisig wallet (such as the required signers and transaction history) are transparent on the blockchain. This can reveal more information about the wallet’s security setup, which might not always be desirable.

- Bitcoin multisig is simpler, protocol-native, and highly secure, primarily used for straightforward m-of-n setups. It’s cost-effective and doesn’t rely on custom code, which minimizes security risks. This multi-sig setup is the basis of inheritance planning at the native bitcoin blockchain level, without any intermediary in a trustless setup without any third party. 
- Ethereum multisig leverages smart contracts, offering extensive flexibility but at the cost of higher transaction fees and potential vulnerabilities from custom code. It’s more suitable for complex setups like DAOs and DeFi applications.