1. CCRL uses BayesElo while CEGT uses Ordo for elo calculation and the differences are quite remarkable.
2. Following CCRL the elo progress since 2006 is 585 elo while for CEGT the elo progress is 778 elo.
3. CCRL in 2006 starts with an 114 higher elo than CEGT but anno 2021 the CEGT rating 79 elo higher.
4. Browsing through the years we see an almost fixed pattern CEGT ratings scoring higher peaking in 2020 with a difference of 87 elo, the year of the NNUE revolution starting with Stockfish 12, see the red marked year.
5. GM Larry Kaufman hinted this is probably due to BayesElo double counting draws.