It could be more exact than Google for certain cases because the aproach is different. I calculate a imagehash(p-hash in my case) like tineye. Googles aproach is not open for the public to know, but probably uses machine Learning and pattern matching. From my own experience the algorithm im using is very fast (approx 1s-2s on a 1ghz single core cpu for one hash+ approx 0.2s for listing similar hashes from a database containing approx 0.5 million hashes, the database is subject to change and is missing many pictures from steemit). But the downside is that i can only find identical pictures and slightly edited pictures, whereas Google can is very good at finding similar pictures, due to machine Learning. Note that i do this project just for fun for me to learn database handling, pictureprocessing and multiprocessing.