Absolute versus relative returns
An asset can rise in dollars while underperforming another asset. Relative-strength ratios remove the common quote currency and compare the assets directly.
ETH/BTC
ETH/BTC rises when Ether outperforms Bitcoin and falls when Bitcoin outperforms Ether. Rolling averages provide a slower reference for the prevailing relative trend.
Dominance
Bitcoin dominance asks a broader question: what share of aggregate crypto market capitalization belongs to Bitcoin? It is affected by the rest of the market as well as Bitcoin itself.
Interpretation
Use relative strength to understand leadership and breadth. Avoid converting every crossover into a trading rule without testing it independently.