"Spring, summer, fall and winter are the seasons."
Translation:De lente, zomer, herfst en winter zijn de seizoenen.
These are cognate to Lent, Summer, Harvest, and Winter in English, which were the usual terms for the seasons in Middle English. As Lent came to have a primarily religious meaning, the poetic term Spring of the Leaf became more common, shortened to just Spring. Similarly, the corresponding term Fall of the Leaf, or simply Fall, replaced Harvest, but it has now mostly been itself replaced by the Latin-derived Autumn. (Also, Lent was originally Lenten, but people started to think of that as an adjective and derived the new noun Lent from it.)
So I just rechecked and in the Netherlands it could be seen as a synonym. But in Belgium we don't use that and "Voorjaar" and "Najaar" are used as Everything before summer and Everything after summer respectively. https://forum.wordreference.com/threads/het-najaar.3237717/ In this topic the same confusion is noted. A movie releasing in "Najaar van 2019" will be releasing between somewhere in september and the end of december.
You do realise that autumn is from 21 September to 21 December and hence is najaar? Alsolso in Belgium they are used as synonyms, e.g..
Sure the terms voorjaar and najaar are perhaps sometimes used a bit more flexible than lente and herfst as they can be used in other contexts. However, this does not mean they are not synonyms.
While jaargetijde can indeed be used for a seizoen, a "seizoen" can also mean a part of the year which is characterized by something or which is suitable for something e.g. the warm season (het warme seizoen), the fishing season (visseizoen) or soccer season (voetbalseizoen). So it's not completely 1-on-1 :)