As background, the Ambassador and Solutel hotels are under the same management and are next door to each other. They are also in the city's "Golden Quad" that includes many embassies, restaurants and shops. In fact, the Ambassador is next door to the French embassy. The maids are dressed in a classic French style. Coincidence?
Solutel is newer. Ask a random local where the Ambassador hotel is, and they likely will know. Ask them about the Solutel, and they likely will not know.
Decor in the Ambassador is generally more formal, and in the Solutel more modern. For example, the breakfast room in the Ambassador shows a news channel on the HDTV (in Russian), while the same for the Solutel shows music videos (in whatever language it was recorded in). Personally, I find the Ambassador hotel breakfast room hot and stuffy. Also, the Solutel has a patio so you can have your breakfast outside, when weather permits.
Breakfasts offer a good variety.
The room HDTVs offer a large selection of channels. However, most are in Russian. In English, BBC, Euronews, Food Network, Fine Living, and a very few others are available.
The hotel photos provided do a good job of representing the hotels and the rooms.
There is only one sauna that is for both sexes, which discouraged my wife from using it: who wants a half-naked old man next to you? Management should consider providing hours of access for each gender.