I am new to LR too, but I had an epiphany that helped me sort things out. I'm not claiming that this is the gospel truth, but it works for me.
LR is for managing images and your workflow.
PS is for manipulating images as part of your workflow.
Confusion is easy as LR has manipulation controls, and PS has incorporated some ways to manage images and workflow.
LR starts with the assumption that you have a library of images. You want to keep the library sorted, and that you may want to use the same image repeatedly, but in different ways. Therefore you work with Export when you want an image to use for the web, to email, or to send to a printer. This is instead of saving copies for each use. If you need different crops you can save a virtual copy for each crop. LR assumes that for each Export what is considered "best" may change, and therefore doesn't save the changes since what is "best" for sending to a printshop may be different than what is "best" for emailing. Therefore there is really only one copy of the image saved. You can (should) save Export Presets for your common uses. Even the uncommon ones since you may be able to change just one or two Export parameters for a one-off Export.
PS assumes that you start with an image, and use PS to make it better. The image when saved is the "best" for whatever use you were editing it for. But, unless you have the original file saved somewhere you may not be able to use the edited image for another use. If you are saving the original image, and then each edited image as you create them, you end up needing massive amounts of storage since each edited image may be saved multiple times. And you now have to keep track of how the edited images relate to each other and to the original.
LR is designed to be able to work with a multitude of images at once (colour correcting an entire shoot). You don't have to (I don't yet) but its built in. PS was designed to work with one image at a time (though it can work with multiples using actions. But I think this is more of doing the same thing over and over i.e. working on images serially).
Hope that helps. Again - I could be wrong... but this thinking helped me get my head around LR.