Hello there! As your question is related to looking for identification/information regarding military personnel, our Guide on Military Identification may be of use to you. It provides a number of different resources, including how to request service records from a number of national agencies around the world, as well as graphical aids to assist in deciphering rank, unit, and other forms of badges or insignia. While the users here may still be able to lend you more assistance, hopefully this will provide a good place to start!

Resting photo: I can't tell his rank since his shoulderboards are not visible. He wears two medals. The photo doesn't have enough detail to make out what they are, but the form factor suggests that they are either the "20 years of the Red Army" or the pre-1943 variants of "For Courage" or "For Battle Merit". He also had two orders: Order of the Red Star and Order of the Red Banner. This was the second highest order in the Soviet award system, so he is considerably decorated. Otherwise he wears a typical post-1943 officer's uniform.

In the later photo he wears shoulderboards of a Major of Artillery. His collection of orders has expanded: in addition to a second Order of the Red Banner he now has an Order of Lenin (the highest Soviet order). His two old style medals are replaced by newer ones, here we see the "20 years of the Red Army" and likely "For Battle Merit" but it's hard to tell from a black and white photo without seeing the face of it clearly. There are three medals in the lower row: the first one could be "For Courage" (again, would be easier to identify if there was colour), then Victory over Germany, then another one that's hard to identify without colour but maybe "For the Capture of Koenigsberg".

There are two resources that can help you if you have his name: Pamyat Naroda and Podvig Naroda. These sites are searchable in Russian and while scans of award orders are provided, there is no OCR and often they are handwritten rather than typed.