Gigahash vs Megahash So, 1 GHash equals 1000 Mhash's as far as I know. Then, why genesis-mining measures the bitcoin hashpower in terrahashes?? 1 Thash = 1000 Ghash. The whole hashocean is said to have 41.6 GH/s. On genesis you can buy 1 Thash for 400$. Who is naming their units in incorrect way?
Your 41.6 GH/s is certainly wrong. According to https://bitcoinwisdom.com/bitcoin/difficulty it's currently 757,561,871 GH/s = 757,561 TeraHash/s.

Also: it's "Tera", one r and capital T. Capitalization is important in the Metric prefixes.  https://en.wikipedia.org/wiki/Metric_prefix

Note also that cloud mining is usually a scam. Why would they give you money? Answer: they don't.