Star Atlas - Greek letter confusion

Does anyone have trouble reading Greek letters on star atlases? The following often look similar under a red flashlight.

Zeta / Xi
omicron / rho / sigma
mu /nu / upsilon

Why are there two variations of Theta? Some atlases use the letter "O" with a line thru it, and others use a "v" with a curl on top, that looks a lot like upsilon. I personally prefer the "O" theta.

"O" theta:
Orion deep map
Stars and planets, princeton field guide
Sky and Telescope
Astronomy, Dec 1996
Uranometria 2000
Burnham's celestial handbook
every Greek language website I looked at

"v" theta:
Sky atlas 2000 delux and field
Night sky observer's guide
Astronomy, Sept 1993

Why? ? ?

Obviously you did not study Greek in high school. For the letter theta, the "O" with a line thru is the printed or typed form, while the one with the curl on top is handwritten or script.