And in case you were thinking this is an isolated case: faaaaar from it.
There are
ى and ا - different letter, same sound.
س and ص - different letter, same sound
ع and غ very different sounds
And my favourite: ذ د ز ر - four similar letters making different sounds
And these are just some selections.
Oh, and each letter looks completely different in a word, because Arabic is always written in a cursive font, where letters are connected to the letter in front and/or behind, sometimes changing the latter shape beyond recognition.