I'm looking to get a laptop for casual use streaming movies using word etc but I'd also like to run dota 2 smoothly on low settings, any suggestions? I'd also like it to have a good battery and light weight. Thank you.
Here are two suggestions. The second laptop with the Core i3-7100u has the newer Intel HD graphics core which is roughly 10% - 15% more powerful than the previous generation Intel HD 520 graphics core. It also has a 1080p screen, but costs $50 more. In my opinion it is worth the extra $50.
I highly recommend you install a second stick of 4GB RAM when you can afford to do so. With two sticks of RAM the RAM will run at full speed rather than at half speed. That can improve integrated graphics by 10% - 15% depending on the game. Also, when running Dota 2 even at 1280 x 720 resolution, Windows, Dota 2 and the Intel HD graphics core will be using more than 4GB of RAM. If there is not enough RAM, then data will constantly be transferred to and from the hard drive which can decrease performance.
The following video demonstrates Dota 2 running on a laptop with a Core i3-6100u and the Intel HD 520 with more than 4GB of RAM installed (probably 8GB). The game is played at both 720p and 1080p resolution. It also demonstrates performance between low and medium settings. Naturally the Core i3-7100u and Intel HD 620 would provide a little better performance.