turning point; change; transition
Refers to a point where something changes, such as a season, era, tide, or situation. Often used in phrases like 季節の変わり目 (change of seasons) or 世紀の変わり目 (turn of the century).
It's easy to get sick at the change of seasons.
I was born at the turn of the century.
point of difference
Archaic usage referring to a distinguishing feature or point of contrast. Not used in modern Japanese.
In old documents, 変わり目 can refer to a point of difference.
変わり目 points to a specific turning point or juncture of change (e.g. the exact moment seasons switch), while 移り変わり describes the whole gradual process of change.
Standard kanji spelling; the most common written form.
Rarely used kanji form; 替 suggests replacement or exchange.
Rarely used kanji form; 代 suggests substitution or generation.
Compound of 変わり (kawari, 'change', the continuative form of 変わる) + 目 (me, 'point' or 'juncture'). The spelling 変わり目 is the standard representation.