If I were faced with a similar problem, I would tackle it perhaps like this:

1. Create backup copy of the offline project.

2. Perform online/offline compare.  Remove all offline blocks that differ from the running/online compare from the offline project.  Note: because you backed up your offline project, you do not lose any work if you mess this up....

3. Upload the missing blocks (after having been freshly deleted.

4. Compare online/offline again.  Repeat 1-4 until everything agrees.

Please suggest better options if people know of them.

engineer.em

To actualize the project.
If I have differences between online and offline (pic 1).
After comparisoni want to upload from device to PC. Tia portal offers me to copy, changing the name and creates a copy of this block (FC17) (pic 2).

After that I have to remove the old block and rename the downloaded. If there is a lot of irrelevant  blocks, then it's a big job.(pic 3)

-        In STEP7, I used to open 2 windows: online and offline and drag drop from online to offline. So the offline project became actual with original names of blocks. How can I do a similar operation in Tia portal without changing blocks names?

http://s3.postimg.org/3upxur3dv/image.jpg

http://s9.postimg.org/jyaaaqylb/image.jpg 

http://s2.postimg.org/lw1iq96wp/image.jpg