Difference between טוּב and טוֹב?
Toov means goodness, kindness or goods (physical), although it's not really used often. Tov simply means good.
Physical goods (such as in economy and business) will always come in the plural form - טוּבין (tuvin).
This ין (in) plural form was influenced from the plural form of the Aramaic language. Grammatically speaking, the form טוּבים is also correct in Hebrew, yet it's not common.
Wetalpaca is correct. You see טוּב in the expression כל טוב (all the best, kind regards etc.). But since "tuv" is uncommon, many people now pronounce this simply as "kol tov".