Hi! Excuse me for always asking about the difference between words in Japanese... here you are another one!

渡す/渡る what is the difference in meaning?

Thank you in advance!

渡す is transitive
渡る is intransitive

Quick primer on transitive/intransitive, if you need it:

http://japanese.lingualift.com/blog/transitivity-in-japanese-grammar/

I used to have trouble remembering which took an object and which didn't, until I learned the kanji in the words for 'transitive' and 'intransitive' in Japanese:

Transitive (acting on something else, the object) is 他動, meaning essentially 'to change another thing'.

Intransitive (acting on oneself, no object) is 自動 meaning 'to change itself'.

Hope that helps.

An example showing their differences:
橋を渡る – to cross a bridge - this is 自動 as the action of crossing the bridge only acts on the person crossing it.

橋を渡す – to build a bridge (over a river), to mediate between two parties – this is 他動 as the aim of the person performing the action is to construct a bridge between the two sides, but not sending himself across it.