# UNS vs CNS Comparison

## High Level Differences between CNS and UNS

| CNS | UNS |
|  --- | --- |
| Implements the ERC721 standard | Implements the ERC721 standard |
| Hosts a single .crypto domain ending | Hosts multiple domain endings |
| Separate resolver and registry contracts | Single contract contains both the registry and resolution data |
| Requires a Resolver lookup call in order to resolve domain data | Does not require a Resolver (RecordStorage) lookup call since all domain data stored in a single smart contract |
| Domain minting governed by MintingController and WhitelistedMinter | Domain minting governed by MintingManager |


### Simplified Architecture

Overall, the main difference between CNS and UNS is that UNS has a simplified architecture which is optimized for higher volumes of transaction and supporting multiple domain endings.

### Easier Data Retrieval

The next difference is that unlike CNS, UNS doesn’t have separate resolver contracts for domains.

* Resolution data is stored within the registry itself which allows retrieving data in a single smart contract call.
* This change removes unnecessary events and functions that were used for setting custom resolvers, thus improving optimizations.


### Simplified Minting Control

Another major change in UNS when compared to CNS is simplified minting control. While CNS is controlled by two smart contracts, UNS has a simpler MintingManager that combines functionality of the old MintingController and WhitelistedMinter.

### More Resources

For a detailed list of breaking changes in UNS, see [https://github.com/unstoppabledomains/uns#backward-incompatibility](https://github.com/unstoppabledomains/uns#backward-incompatibility).