A concrete starting point
4/4: 1 & 2 & 3 & 4 & · 6/8: 1 la li 2 la li
Simple meter and the written unit
In 4/4 a bar contains four quarter-note units, often felt as four beats. In 3/4 it contains three. The quarter can divide into two eighths. A metronome set to four beats per bar supplies a simple accented reference, but an accent pattern does not encode the full rhythmic character of a piece. Tempo markings must specify which note value receives the BPM.
Compound meter groups threes
6/8 contains six eighth-note units usually grouped as two dotted-quarter beats. 9/8 and 12/8 often group into three and four dotted-quarter beats respectively. At dotted quarter = 60 BPM, each eighth-note subdivision occurs at 180 per minute. A simple quarter-note BPM field cannot silently be treated as a dotted-quarter field; state the beat unit explicitly when converting.
Compare a grouping rather than just a number
Clap six evenly spaced subdivisions. Accent positions one and four for two groups of three, then positions one, three and five for three groups of two. The elapsed subdivision grid stays the same while the grouping changes. Use a polyrhythm tool to inspect simultaneous pulse divisions, but do not equate every 3:2 pattern with a complete time-signature analysis.
Put it into practice
These examples describe explicit written notes and relationships. A diagram or generated phrase does not replace listening to a complete musical context, choosing a comfortable register or checking a physical technique with a teacher.