Font Gallery: What is the point of XDP providing same fonts in TrueType/PostScript?

[cadudesun]

Hi,

I'd appreciate your help.
In XDP v17 Fonts Gallery, there are available two sets of the same fonts: TrueType and PostScript (image below).
a) I read somewhere that PostScript is a legacy format, so what is the point of XDP providing the PostScript fonts? Why not just deliver the TrueType set?
b) Assuming that having the TrueType set I will not have the need to use the same PostScript fonts, I intend to delete the latter to clean up the Gallery. Is that OK? Or would I miss something later not having PostScript fonts there?

Thank you,
Carlos