In most of the universities in the USA/Canada, they want 3 letters of recommendation (LOR). I am curious to know do the admission committee reads or reviews all 3 LORs equally or do they give more precedence to the recommendation of the first recommender and the least precedence to the last one.
No, they aren't all the same, but it depends on what they say, not the order they are listed or received.
The best letters will come from people who say they have worked closely with you in some way, perhaps supervising a project; research even better, but rare. They will also confidently predict your success.
Lesser letters will be those that say something like they had you in class (or classes) and you did well, but don't put their own reputation on the line with a prediction.
Everything in between.
If a letter like the first above is from a prominent person in the field you intend to study, even better, but not so much for the second sort of letter.
Also, sending fewer than the expected number is a red-flag in most cases.