Until earlier this month, bitcoin and Bitcoin Cash addresses used the same format, making it difficult to ensure you were transacting using the correct currency’s address. In order to simplify the process for transacting with both bitcoin and Bitcoin Cash for our users, Blockchain wallets are now using an a new format (CashAddr) for Bitcoin Cash addresses.

Q: Why do my Bitcoin Cash addresses look different?

A: Bitcoin Cash developers have proposed a new format for addresses to help differentiate between bitcoin and Bitcoin Cash addresses, called CashAddr. This updated format only changes how your Bitcoin Cash addresses are displayed, not the underlying private and public keys.

Q: Why has Blockchain implemented this change for users’ wallets?

A: We want to continue improving the user experience for both bitcoin and Bitcoin Cash within users’ wallets. Ultimately, having a different address format for each will help you distinguish which currency you’re transacting with, allowing you to use BTC and BCH more easily.

Q: What is the difference between the address formats?

A: Bitcoin Cash addresses now look like this: qp3wjpa3tjlj042z2wv7hahsldgwhwy0rq9sywjpyy. They can also have a prefix (bitcoincash:qp3wjpa3tjlj042z2wv7hahsldgwhwy0rq9sywjpyy). Each Bitcoin Cash address also has a “legacy address”, which is it’s corresponding bitcoin address. You can find the legacy address for each BCH address on Blockchair. Take a look here to see an example of the difference between legacy and CashAddr addresses.

Q: What do I need to do?

A: Nothing, we’re taking care of it for you! Your wallet will now only show Bitcoin Cash addresses in this new format. The only thing we encourage you to do is to start sending and receiving using the updated address type.

Q: Can I still send to the original ‘legacy’ address?

A: Technically yes, but it would benefit both you and the community to begin using the new version. Don’t worry, if you have a legacy address that is currently being used, it will continue to work. If you continue transacting with your legacy addresses, they will be displayed in your transaction feed as the BCH CashAddr address equivalent.

Q: Is this a protocol change, soft-fork, or hard-fork?

A: Nope.

Q: Where can I dive into more technical details?

A: You can find more details on this update here:
https://github.com/bitcoincashorg/spec/blob/master/cashaddr.md

source:
https://blog.blockchain.com/2018/01/23/cashaddr-bitcoin-cash-addresses/