in regards to alphabet variation...
Weight – variances in character weight include light, medium, bold, semibold, heavy, and black.
Width - Most typefaces can be condensed or extended, which provide variations in character width.
Style is a very general term that includes many characteristics of a typeface.
in regards to measuring type...
How is type measured in inches, mm, points or picas?
1 inch = 6 picas = 72 points
A typeface is measured from the top of the capital letter to the bottom of the lowest descender, plus a small buffer space.
Point measures type from the top of the ascender to the bottom of the descender. Used to measure height of type size and the space between lines and paragraphs.
Picas measure width, such as the width of a typeset column (length of line) or the space between columns.
How many points in an inch? There are 72 points in an inch
If a letter is set in 36 pts about how many inches tall is it? It is 3 picas, or 1/2 an inch
How many picas in an inch? There are 6 picas in an inch
How many points in a pica? There are 12 points in a pica
X-height is the height of lowercase letters, or the height of a lowercase x, in proportion to the ascenders and descenders. It effects the feel of a typeface and how easily the text can be read.
Cap height is the distance from the top of a capital letter to its bottom.
Leading is the space between lines of type.