Hi!

Difference is just the colour. Times are changing. There was a time when entry-level models belonged to the Hobby programme and could be recognized by the colour of the bar on the box.
Then came the MyWorld programme. Parts of the MyWorld programme were moved to the StartUp programme. New names, new boxes, same moulds.

Changing legal requirements can lead to different age declarations.

Marklin have always had two levels of standard for their freight cars. Since the 1980s the cheaper, more basic wagons are in the 44xx(x) series, and the more accurate models are in the 46xx(x) series.

The 44xx series were preceded by the 45xx series which mostly had tinplate chassis and bodies with minimal detail, although the American range of wagons in recent times have sometimes also used 45xxx. All current 44xxx wagons have Relex couplers.

As the numbers have been used up in the 46xxx they have moved on to 47xxx and 48xxx numbers for the higher quality wagons. All of these, from the 1990s onwards, have been fitted with close couplers

Both 4440 and 4441 appeared in the catalogue in 1977. 4440 is still in the catalogue, 4441 was in it until 2010/2011.
So old versions of these cars will have "Made in Germany" or "Made in Western Germany" engraved at the bottom. If your cars have no engraved "Made in ..." they will be from this century.

The boxes should have a print code that indicates month and year of printing. In over 30 years those cars will have come in several different boxes.

Rolling stock with four-digit ref. numbers appeared in the catalogue before 1996. There are not many of those "dinosaurs" left.


Update: 4440 had a silver tank in the 1977 catalogue (it looks silver, but could also be light grey), in later years it had a white tank, and finally in the second half of the '80s it had a blue tank.
Three different liveries for the same ref. number.