Not entirely sure what you're looking for here, but I'll guess it's the meaning of "optical zoom" specs on PTZs.
In that case, the OPTICAL zoom number (10x, 16x, 22x, etc.) is merely a ratio of the shortest to the longest focal length the lens. A 10x optical zoom, for example, could indicate a lens that varies from 3-30mm, or 5-50mm, or 10-100mm, or any other factor of 10. A 22x zoom might be 3-66mm, 10-220mm, etc.
All this tells you is the overall range; it gives no indication of the actual FOV of the camera at either end of its range. For that, you need to know the actual focal length at either end of the range, and the imager size, and then use one of the calculators linked in your other thread.
The other feature most PTZs have is "digital zoom" - what this refers to, is the camera electronically cropping the image, and then expanding that to fill the display. It doesn't give you more detail, but it may help you pick out things you wouldn't see otherwise. Ultimately, you can do the same thing by loading the image or video into software and zooming in there.
As far as HD (high definition, generally megapixel and above) vs. SD (standard definition, or around 704x480 or 0.3MP), HD will certainly capture more detail and allow more digital zoom, but iIn short, "digital zoom" generally goes way down the list of features you need to worry about.