MCC is a hex dump that most players, and people, cannot read. VTT is what web video players and browsers display natively. MCC is at home in closed captions for broadcast and streaming delivery that carry CEA-708 as well as CEA-608; VTT is the usual choice for captions on web pages and in HTML video players.
The text is read as UTF-8 or UTF-16, whichever the file is. An older file in another code page is read using the charset it declares, or as Windows-1252 if it declares none, so accented letters in an unlabelled legacy file can come out wrong. A file that is not text, such as the picture-based subtitles of a DVD, is refused instead of being converted to nonsense. Of the styling, only italic, bold, underline and the position on screen (top, middle or bottom, left, centre or right) travel between formats; fonts, colours, outlines and effects do not. The CEA-608 caption data inside each packet is read, as for SCC. Captions that exist only as CEA-708 service data are not read. Top and middle positions and left or right alignment are written as WebVTT cue settings.