What would be the difference in meaning between 違っていた and 違った?


> 昔は違っていた。
>
> 昔は違った。
>
> It was different a long time ago.

Do these two Japanese sentences mean the same thing?

Here is the sentence in the original context. The translations are not mine,
but are supplied by the Japanese writer. If I replaced 昔は違っていた。with 昔は違った。,
how would the meaning change?

> February is the coldest in Japan. 日本は2月が一番寒い。
>
> It was different a long time ago. 昔は違っていた。
>
> There were ages where it was the coldest in December or January.
> 12月や1月が一番寒い時期もあった。
>
> But now, you can say February is the coldest month. しかし、今はやっぱり2月が最も寒い。
>
> The seasons are getting shifted little by little according to global
> warming. 地球の温暖化にともない、季節もだんだんずれ始めている。




> 昔は違っていた。=> It was different a long time ago. (for a period)
>
> 昔は違った。=> It was, once, different a long time ago. (for a moment)

