I export AI artboards at both 72ppi and 300ppi. The AI data is only vector, and contains some text. When I compare the two exports (on a screen), the text in the 72ppi one seems "bolder" than the 300ppi one. I understand it may just be that, at the lower density, text isn't going to be as sharp, but the difference is very noticable.
In the past I've kept multiple artboards for each illustration with the differences just being the scale (about 1.5 times). I'd then export the larger scale artboard at 72ppi and the smaller scale at 300ppi. It's been awhile since I started the practice and not sure why, but it makes me wonder if there a way, like with scaling the AI data, to have exported images look closer to the same when displayed.
The attachment is a Word page with the 72 and 300ppi PNG files inserted.
If you are exporting as PNG files then resolution will certainly make a big difference in the appearance of the resulting files. This will especially be true for any enlarging of the files that may be necessary. This is because PNG files are not, in any way, vector files. They are raster and are subject to pixelization that occurs as the files change sizes.