What's the difference between a 20V, 40V and 56V trimmer?

Higher voltage generally means more cutting power and longer runtime, but also more weight and cost. Verified-purchase reviewers tend to recommend 20V models like the WORX WG163 and Black+Decker LST522 for small, flat yards where light weight matters most, and step up to 40V or 56V (EGO, Greenworks 40V) for larger lots or tougher weeds.