.NET 9 will be available shortly. The main focus in .net 9 is
Cloud-Native focus.
Performance enhancements
Net features in security, LINQ, and Cryptography
SDK improvements
.NET 8 is long term support. it means, .NET 8 will have long support rather than .NET 9. If you already developed in .NET 8. There is no need to upgrade. But if you want to build Cloud app in native way, better JSON API management and LINQ. You can use .NET 9. Please note that .net 9 is standar term support while .net 8 LTS it means.
Support Duration: LTS offers a longer support period (3 years) compared to STS (18 months).
Stability vs. Innovation: LTS focuses on stability and long-term maintenance, while STS provides quicker access to new features and improvements.
Upgrade Frequency: STS users need to upgrade more frequently to stay supported, whereas LTS users can remain on the same version for a longer time.