The two photographs you have posted show that the soyuz middle section is longer than the corresponding re-entry module of Soyuz.
You can also see the differences between the Soyuz and Progress here Wiki. They are significantly different in that for Progress the re-entry capsule has been replaced and the ISS crew have no access other than to the orbital module.
The following text comes from the same wiki page:
The reentry module of the Soyuz was replaced with an unpressurized propellant and refueling compartment with ducting along the outside of the spacecraft. This meant that if a leak occurred, the poisonous gas would not enter the station's atmosphere. The fuel is carried in two tanks.
The wiki page also shows these diagrams:
Thus you can see that the Progress is quite different, not at all "essentially the same", as replacig the re-entry module with a module for carrying propellants completely changes the concept of operations of the vehicle.