The blessings before and after each aliyah are very similar. Today in synagogue someone accidentally began reciting the wrong one, which got me thinking about them.
The parts of the two blessings which differ are:
אשר בחר בנו מכל העמים, ונתן לנו את תורתו
אשר נתן לנו תורת אמת, וחיי עולם נטע בתוכינו
Each of these lines has one topic in common (the giving of the Torah), and one topic different (choosing us from the nations, and eternal life).
Why do these topics appear, and in the places they appear?
Perhaps the answer is that choosing us as a nation happened in the *past*, so it is mentioned in the earlier blessing, at the beginning of the blessing. Whereas eternal life is the reward we get in the *future* for Torah observance, so it is mention in the later blessing, at the end of the blessing.