1. I don’t know the specific differences. From the appearance, the three fonts are somewhat similar, but there are subtle differences in specific character height and width ratios, character size, and default line spacing. of.
2. The reason why you cannot type "Kaitai" is because there is no file of this font in the font folder of your Windows system files (it's a bit strange, generally speaking, KaiTi is the default default for all versions of the Windows system. one of the font files included).
Just download a font file from the Internet. You can also download many font files that are not available in new systems from the Internet. Some of the more useful websites are: /index_1.html
After downloading, extract the file with the suffix .TTF (or .ttf) to the C:\Windows\Fonts folder. Then reopen the document such as Word, and you can find the corresponding font.