Are the individual silent shemoneh esreis of maariv, shacharis and mincha of Rosh Hashanah identical? Also, are the individual silent shemoneh esreis of Yom Kippur; maariv, shacharis, mincha and neilah identical?
A quick check of a small selection of nusach Ashkenaz siddurim (Birnbaum, Tefilloh Sefas Yisroel, ArtScroll, Koren, Rödelheim) indicates that the 'Amidah for Rosh haShannah is the same* for all tefillot, except for Musaf.
For Yom Kippur, 'Arvit, Shacharit, and Minchah are the same, while Musaf and Ne'ilah are each unique (the latter has an identical nusach to the regular Y"K 'amidah through ברוך עושה השלום). All tefillot of Yom Kippur have viduyim, except for Ne'ilah (in most nuschaot).
*All Ashkenazi siddurim replace שים שלום with שלום רב for 'arvit and minchah on weekdays. Most Eastern-Ashkenazi siddurim also do so by minchah on Shabbat.