Roku's is pretty much content from the Roku Channel, along with selections from some live streaming services. Yeah, that's a description of what Amazon Fire TV offers, but the details are different.
The only real live TV guide is actually within the Roku Channel. If you have Pluto TV, or Xumo, or Sling TV Free, or any of a number of other free live streaming apps, you won't find them in one place. And where it does have links to other services, it's simply links to those apps, whether or not you have them installed. You'll see in a minute why I bring this up.
Again, Roku's Live TV section is not as useful to me as Amazon Fire TV's. So let's see what I like about Amazon's setup.
The Fire TV section for live TV is called "On Now," which actually is a good description when you think about it. There is a guide that brings in many channels (not all) from services you have, not services they suggest.
Remember when I said that Roku has links to apps whether or not you have them installed? Amazon only lists content from apps you have installed, and have configured to work with the On Now functionality.
After you launch the On Now guide, pressing the Menu button on the remote lets you configure the service. You can add or remote services (actually hide or show the source) and arrange them. And within each service, you can pick and choose which of the available channels show up in the On Now guide. I like that approach much better.
You can even select favorites, and they'll be listed at the top, regardless of the order of the services selected. The favorites will still show up within the sections for each service. Oh, and if you pick a channel as a favorite in two different services -- there is some overlap on these services, after all -- they will show up twice.
When you select the content to view, it does open the corresponding app, but unlike Roku, it only picks from installed apps. And with content from multiple services all in one place, it is far superior to Roku's offering.
If you've read many of these posts, you know I'm in the Roku camp when it comes to a primary streaming app. Regarding this type of feature, however, Fire TV is far ahead of Roku. If this is important to you, and you have a hard time deciding between Fire TV and Roku, this may be the factor to push you to the Amazon Fire TV camp, and have that platform as the basis of your Streaming Life.