der Übertritt
switch
A person’s change from one group, party, religion, or organization to another.
Der Übertritt des Abgeordneten zur Oppositionspartei sorgte für Schlagzeilen.
The lawmaker’s switch to the opposition party made headlines.

switch / crossing
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switch
A person’s change from one group, party, religion, or organization to another.
Der Übertritt des Abgeordneten zur Oppositionspartei sorgte für Schlagzeilen.
The lawmaker’s switch to the opposition party made headlines.

'Der Übertritt' is the noun form of the verb 'übertreten' (to cross over/violate). The basic idea of 'stepping over something' or 'crossing a boundary' appears in all meanings: you switch to another party, step over a line, or a river overflows its banks.
Sein Übertritt zu einer anderen Religion überraschte die ganze Familie.
His conversion to another religion surprised the whole family.
When someone changes to another group, the preposition 'zu' (+ dative) is used. People speak of 'Übertritt zu einer Partei' (switch to a party) or 'zum Christentum' (conversion to Christianity).
Der Übertritt des Spielers zum Konkurrenzverein wurde offiziell bestätigt.
The player’s switch to the rival club was officially confirmed.
The context makes the meaning clear: politics or religion points to a change of group. Sports terms like 'Wurf' (throw) or 'Sprung' (jump) indicate crossing a line. Words like 'Fluss' (river), 'Ufer' (bank), or 'Hochwasser' (flood) signal the nature-related meaning.
Der Weitsprung war ungültig wegen eines minimalen Übertritts.
The long jump was invalid because of a minimal line crossing.
change / switch
'der Wechsel' and 'der Übertritt' can both describe a change from one side to another. 'Wechsel' is very general and fits many situations: work, school, a club, an opinion, or a system. 'Übertritt' is more specific and is used mainly when a person moves from one group, party, religion, or organization to another. It often sounds more official than 'Wechsel'. If something is simply being replaced or changed in a general sense, 'Wechsel' is more natural. If the focus is on joining a new group, 'Übertritt' fits better.

Ihr Übertritt zu einer anderen Partei wurde in den Nachrichten besprochen.
Her switch to another party was discussed in the news.
Der Wechsel in eine andere Abteilung war für Mehmet zuerst ungewohnt.
The switch to another department was unfamiliar for Mehmet at first.