There is also a table if you click on avisynth+ formats
http://avisynth.nl/index.php/Avisynthplus_color_formats
As you can see YV12 is a shortcut for YUV420P8. Y10 is Luma channel in 10bit. But yes this shit is confusing and I have to look it up too. What's why I like this notation more YUV420P8.
But I guess it makes a bit more sense with this graphic:
YV12 needs 12bytes for storage. (
https://en.wikipedia.org/wiki/YUV)