Import into Roon from ITunes VS re-import the folder themself

HI Everybody
New to Roon .
Nearly ending the trial right now. So far loving it .
I need now to import my old iTunes library and was wondering …
What is the difference between “import the XML” … or "re-import the different folder " into Roon …
Really I do not really care about my old playlist …
Does that change anything ?
thanks for the reply !
Phil