The difference is due to conjugation: they are pronounced identically, but are used with different pronouns:
Je bois - Tu bois - Il/elle/on boit
Nous buvons - Vous buvez - Ils/elles boivent
It's just like German where you say Ich trinke, but du trinkst and er trinkt - the verb ending changes depending on the pronoun used.
"Bois" is used for 1st and 2nd person singular; "boit" is for 3rd person singular. https://www.thoughtco.com/introduction-to-french-verbs-1371059