My watercolor sketchbook is more textured on one side

Idk what sketchbook it is as it is gifted, the only thing which hint sth is a gold coloured word which is finenolo on the black cover, it also has a elastic band.

The paper texture is quite inconsistent, the first 2 pages are very textured, but then the next 2 pages are more smooth but still lightly textured.

What sketchbook is that, and should i use the less textured side for watercolour too or is it best to avoid