Sauron was 'greater', effectively, in the Second Age than Morgoth at the end of the First. Why? Because, though he was far smaller by natural stature, he had not yet fallen so low.
---
Morgoth had let most of his being pass into the physical constituents of the Earth - hence all things that were born on Earth and lived on and by it, beasts or plants or incarnate spirits, were liable to be 'stained'. Morgoth at the time of the War of the Jewels had become permanently 'incarnate': for this reason he was afraid, and waged the war almost entirely by means of devices, or of subordinates and dominated creatures.

Sauron, however, inherited the 'corruption' of Arda, and only spent his (much more limited) power on the Ringss; for it was the creatures of earth, in their minds and wills, that he to dominate. In this way Sauron was also wiser than Morgoth. Sauron was not a beginner of discord; and he probably knew more of the "Music" than did Melkor, whose mind had always been filled with his own plans and devices, and gave little attention to other things.
---
I t.n... tva ot "Melkor Morgoth"

Znachi, iasno, che Melkor ima po default MNOGO po-ogromna sila ot sichki, prosto ia polzva typo i hem ia gubi, hem vse edno ia niama... neadekvaten, nepoznavasht zemiata (shtoto e blial dokat tatko mu pial pesni i t.n.). A Sauron investira razumno mnogo po-malkoto si sila i.. voila! :)