The Smart Band 7 is very similar to the Smart Band 6 at first glance. However, the AMOLED display grows considerably in the current fitness tracker generation and also has an always-on function. However, the Xiaomi Mi Band 7 still lacks an important feature for athletes. https://www.notebookcheck.net/Xiaomi-Smart-Band-7-review-Good-fitness-band-with-wasted-potential-amp-uncertainties.640636.0.html
Very good review.
" However, there are no major differences between the apps."
Nice review of the band. However the two apps does have major difference for the band and for the Xiaomi ecosystem.
As an example, Mi Fit allows you tu set goals in steps, weight, calories, stand up time, whereas Zepp Life only allows to set goals for weight and steps. Mi fit sync with STRAVA, Zepp life does not.