وَيَتَرَسَّلُ فِي الْأَذَانِ، وَيَحْدُرُ فِي الْإِقَامَةِ
Translation: He gives the adhan slowly with pauses and pronounces the iqamah at a quicker pace.
Tarassul means delivering adhan words clearly with measured pauses. Hadr means giving iqamah in a relatively brisker, connected fashion.
Brisk delivery must not distort the words: accuracy of pronunciation remains important in both.