You gave two different verbs and two different "people" (Едете is second person formal/plural [you] of ехать, and ездим is first person plural [we] form of ездить). You can see how ехать conjugates at: https://ru.wiktionary.org/wiki/ехать , and the conjugations of ездить at https://ru.wiktionary.org/wiki/ездить.
Ехать is the unidirectional verb of motion that implies that transportation is used. Ездить is the multidirectional verb of motion that implies that transportation is used.
In this sentence, they say that they go to Moscow every summer. Because of this, it's best to use the multidirectional verb of motion - you are going there and coming back home. If the sentence was "This summer we are going to Moscow", the unidirectional verb is better (Этим летом мы едем в Москву).
can't drive be used here? every summer we drive to moscow
https://en.wiktionary.org/wiki/%D0%B5%D0%B7%D0%B4%D0%B8%D1%82%D1%8C#Russian Verb е́здить • (jézditʹ) impf (perfective пое́здить)
to go (by horse or vehicle), to ride, to drive to come, to visit