The Mac will cost $700 extra, and come with a higher-resolution display, a quad-core processor, and more RAM. That may be a better deal for her if she plans to do a whole lot of work directly on the laptop, rather than using the laptop to access remote computers.
Or you know, you could configure the ThinkPad you are buying to have a quadcore and a 3K screen. Note that with the same CPU the ThinkPad will be faster than a MBP by being thicker and having much better cooling. Mac's CPU are really only good in short sprints, for intensive load you need something like a ThinkPad.
RAM can be upgraded by the user. So you can also save money in taking a smaller option (just choose a 1 DIMM one), and then add more ram yourself. This is installable through a hatch on the botton, doesn't even require opening the body.
If you need even more GPU and CPU power, get the ThinkPad W line.