How does the biological age calculated correlates with the alternatives measuring the biological age, e.g. epigenetic clock?

There was a recent study done by Edinburgh University of 11 different multi omics clocks, concluding; GlycanAge and methylation based clocks track generalised ageing, while others capture specific risks. GlycanAge is better at detecting biological age, methylation clocks are better at detecting chronological age. Acceleration of methylation based clocks doesn't correlate with subsequent hospital admissions or risk factors, acceleration or glycan based clocks correlates with risk factors (future incidence of disease) and subsequent hospital admissions, beyond the known risk factors considered in the study. Reference is available here https://www.aging-us.com/article/203847/text