1. File Compression Efficiency: xz generally provides better compression ratio compared to zstd. It can compress files more efficiently but at the cost of slower compression and decompression speeds.
2. Speed of Compression and Decompression: zstd is significantly faster in terms of both compression and decompression compared to xz. It offers a good balance between compression ratio and speed, making it suitable for scenarios where speed is crucial.
3. Memory Usage: zstd is more memory-efficient than xz, requiring less memory during compression and decompression processes. This can be advantageous in systems with limited memory resources.
4. Compatibility: xz has been around longer and is supported by a wide range of operating systems and software. zstd, on the other hand, may not be as widely supported in all environments.
5. Streaming Support: zstd offers better support for streaming data processing compared to xz. This makes it more suitable for use cases where data is being processed in real-time or in a continuous stream.
6. Feature Set: zstd provides additional features such as dictionary compression and multi-threading support, which can enhance its performance in specific scenarios.

In Summary, xz and zstd differ in compression efficiency, speed, memory usage, compatibility, streaming support, and feature set.