I've taken an unusual step, and installed the just released Mac OS 10.15 codename Catalina, rather than waiting a few weeks.

There are some differences especially if you have other Apple environment devices, as you can now use iPod apps on your Mac. There's new media apps, Music replaces iTunes, Apple TV, Podcasts etc. plus the usual security updates.

If, as I do, you just use Macs and not iPhones or iPads etc. there's not that much which is new. Beware though it's an 8GB upgrade!

https://www.apple.com/uk/macos/catalina/features/