At different meeting, votes can be given or tendered. Could you explain to me the difference between "to tender a vote" and "to give a vote"? Or are they synonyms?
Yes, tendering is giving. But it's usually used more in the sense of giving or offering something formally after thoughtful consideration and in expectation or hope of acceptance. I probably wouldn't say that I tendered you a book, flowers, or money. I mostly hear it in the context of submitting a letter of resignation from a job or position. "He tendered his resignation" means he submitted a letter of resignation and awaited (or is awaiting) a decision on the part of his employer. Something tendered might be accepted or rejected.
It's more poetic than everyday conversational, but I could tender you my thoughts (or anything else). That would imply that I formally offer them to you for your consideration and acceptance.
I'm not sure why someone would say "tender" rather than "give" a vote, other than to add the element of formality and offering. In my part of the world we seldom say or hear either "tendered a vote" or "gave a vote", but just "voted".