Is there a difference in meaning between להגדיל and להגביר?
I've seen both used to translate the English transitive verb "to increase"? Do the two Hebrew verbs mean exactly the same thing? If not, how do they differ in meaning? When would you use one vs. the other?
They're somewhat different. להגביר is to turn up or increase something that is normally not tangible, such as volume or some signal. להגדיל carries a more physical meaning and means to grow something or make something bigger.
It could be that there are few exceptions to this rule, but that's it for the most part.
The verb להגדיל essentially means 'to make something bigger' (to enlarge), while להגביר 'means to make something stronger/greater' (to boost). Examples: "You need to make this screen bigger" - "אתה צריך להגדיל את המסך הזה." "We have to turn up the volume!" "אנחנו חייבים להגביר את העוצמה!"