Yes, the author expressed it a bit clumsily.

Duplo is the oversize brick line for smaller children.

And it has train sets. Lego used to have train sets, several systems, in fact, but they stopped doing that.

Well, always, the Lego City line has some trains with tracks, but it‘s not really a train system like the old ones.

Duplo are blocks twice the size of Lego.

There are also Quatro blocks which are twice the size of Duplo. These have been discontinued: http://lego.wikia.com/wiki/QUATRO

Duplo is the brick line by Lego with twice the linear dimension of Lego per “dimple”.

This does make them more suitable for younger kids (because they are less likely to be choking hazards and require less fine motor skills)

My thoughts exactly [1].

[1] https://en.wikipedia.org/wiki/Lego_Duplo