Both of them will do fine for Lightroom as both are capable of doing any processing work, as well as uploading and posting online. The matter of deciding which to go for, should not be based on the technical sides, it should be based on how and where you handle them.
A laptop, as the name implies, is a form of portable computer that you can prop up on your lap. You do not have to hold the computer to steady it, or to keep it upright. You just balance the laptop, adjust the lid, adjust your legs, and take your hands off. You can place it on anywhere, a desk, kitchen counter, bed, etc., and it just stands upright, all you have to do is adjust the lid to get a suitable angle of view.
A tablet, like the iPad Pro, is a flat-like-a-tray machine that needs to be put flat down on a surface, on your lap, wherever. But you would need to hold it up yourself, so you would be using one hand to keep it upright. Unless you opt for to buy a cover case that can be folded into a stand.
On the other hand: A laptop does mean a slight bulky object as laptops tend to be thicker than tablets, and it does mean you need to open the lid so you can view the monitor, whereabouts with a tablet like the iPad, they are thinner and quicker to look at, since you're in effect looking at the screen already (unless you're using a cover case).
As a photographer, you would decide between a SLR and a compact camera depending on where you're going and what you're doing. For example, if you are going somewhere where you can carry your camera bag, you would opt for the SLR. But if you're going somewhere where a camera bag would be getting in the way, you would opt for a compact camera which you could slip into your pocket. Same with hardback book v paperback book, lightweight jacket v long heavy coat, etc.
So you just use your life experience and your photography experience, to think about how would you carry around a laptop or a tablet. You need to decide between a laptop or an iPad by thinking about how, where, and when would you carry either of them around the house, how often would you use them, and all that.
In my case: I already have a desktop computer that is always readily available for me to use, all I have to do is go to my desk, and use my desktop computer. So there is no need for me to use a laptop in the home. Why fold a laptop, take it to the kitchen, open the laptop, fold it, take it back to the living room, when all I have to do is just pop to the living room and grab the mouse? That is why I chose an iPad as I can carry it anywhere and just take a quick look at the screen.
It is not about the chips inside the machines, it is not about the CPU or the RAM, it is about how to carry them around and handle them.
If you're likely to be leaving your computer in one spot for hours, like you leave your computer in the kitchen almost half the day, then take it to the living room, and leave it there for the rest of the day, then maybe a laptop would do better, since you could just open the lid, and leave it standing there on the kitchen counter.
But if you're going to keep bringing the computer around wherever you go, even to the toilet, then you could benefit from an iPad.
Hope this helps you decide on which to opt for?
