[t͡s] is one doubly articulated consonant.
[ts] are two separate articulated consonants.
When the sounds [t] and [s] appear inside the same syllable, they are always pronounced as [t͡s], no matter if they are written as »z«, »tz«, »ts« or as »t«:
plötzlich = [ˈplœt͡slɪç]
schätzen = [ˈʃɛt͡sn̩]
Platz = [plat͡s]
zu = [t͡suː]
zwei = [t͡svaɪ̯]
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