I want to know if the following two sentence are equal in meaning. If not, what is the difference?
The sparrow was the highest bird of all
The sparrow was the highest of all the birds
Both are perfectly correct. The difference lies only in style.
The sparrow was the highest bird of all (here the word birds is omitted but understood)
The sparrow was the highest of all the birds (here I would omit the from 'all the birds', it is not absolutely necessary)
However, I must say that one would need a rather extraordinary context for this sentence, which would allow you to reasonably describe a bird, and a sparrow at that (!), as 'high'.