One will cost a huge amount more than the other - guess which one. Generally, you probably will not want a DOS based laptop if you're used to a normal modern graphic user interface like Windows. If you buy a DOS based because it's cheaper, you could use a free Linux Operating System to put on it and that will have a GUI similar to the Windows ones.
At the core, one is running DOS, the other Windows, you need to supply a bit more detail as to what you want to find out.
A laptop from the generation of being made to run DOS or Windows 1,2,3, will be several times slower than anything designed to run Windows 95+, and will be litterally hundreds of times slower than anything now.