As a great lion. לָבִיא, generally translated "old lion," as in Genesis 49:9. By some it is rendered lioness (cf. Job 4:11; Nahum 2:12). As a young lion. אַרִי, the ordinary term for a lion without further distinction.
It is altogether fantastic to suppose that Balaam had just seen a lieu coming up from the ghor of Jordan, and that this "omen" inspired his "mashal." The rising of a lion from its covert was one of the most common of the more striking phenomena of nature in those regions, and the imagery it afforded was in constant use; but in truth it is evident that these similes are borrowed from Jacob's dying prophecy concerning Judah (Genesis 49:9), in which the word "prey" (Hebrew, טֶרֶף, a torn thing) is also found.
Balaam was acquainted with that prophecy, as he was with the promises made to Abraham (cf. Genesis 49:10 with Genesis 13:16; Genesis 28:14).