While Lightroom is generally used for cataloging, global edits, and basic local edits and Photoshop is used for more advanced post-processing, there is a definite overlap between the features and capabilities of the two applications. This great video details when you should use Photoshop versus when you can afford to stay in Lightroom.
Coming to you from Nigel Danson, this helpful video discusses when you should consider using Photoshop versus when you can stay in Lightroom, particularly as it applies to post-processing landscape images. When it comes to editing, you can certainly accomplish anything you can do in Lightroom in Photoshop, plus way more, but a lot of photographers (myself included) prefer to keep everything in Lightroom if possible. I think a lot of photographers are surprised by just how much editing is actually possible in Lightroom, even on the local level. While it will not ever match Photoshop, it is worth taking time to explore the app's capabilities more closely. Check out the video above for the full rundown from Danson.
And if you really want to dive into landscape photography and how to edit images, check out "Photographing The World 1: Landscape Photography and Post-Processing with Elia Locardi."
It's not really a VS, start by dumping pics into Lightroom, do easy edits and export or for more advanced, send over to Photoshop and do bigger edits, save and they go right back to Lightroom where you can add global color grading and then export. More like a team.
Adobe photography pack has both for a reason. PS is an editor, not a DAM like LR. Both work together. PS cannot manage your images, tagging, location etc and LR cannot do edits...Not even a simple composite.
I have not used photoshop (or any equivalent) for a number of years. Currently, I just use Lightroom Mobile. I find no need to leave LR, I don’t want to.
Or you can use ACDSee Ultimate instead. You can do pretty much everything Lightroom and Photoshop do in one place including, catalog, develop, edit.
ACDSee Ultimate is Windows only. The Mac version is very basic.