To compare the apartments you like, and choose the most suitable one - use the feature To comparison.
In order to do this tick the check-box To comparison to the apartments you want to compare. Then click on the In comparison to compare the selected apartments.
If the flat, you are interested in, is open in a separate tab, you do not need to go back to the general list of apartments to tick To comparison - you can do it directly in the tab.
You will be able to view all the characteristics (such as cost, district, area, etc.) and attributes (the availability of Wi-Fi, washing machine, cable/satellite TV, number of sleeping places, etc.) of the apartments you have chosen at the same time, and do not move from one tab to another, in order to decide what apartment is more suitable.