What are the common terms for these kinds of notebooks?
In British English the first is feint-ruled paper or simply ruled paper.
English: feint-ruled paper Definition of 'feint-ruled paper' feint-ruled paper in British English (ˈfeɪntˌruːld ˈpeɪpə) NOUN writing paper with light horizontal lines printed across at regular intervals Collins English Dictionary. Copyright © HarperCollins Publishers
Feint-ruled paper or simply ruled paper
(of paper) marked with parallel straight lines
Marked with squares or rectangles
It differs from graph paper by being evenly ruled, whereas graph paper has stronger 5th and/or 10th lines.
Definition of legal pad : a writing tablet of ruled yellow paper that is usually 8.5 by 14 inches (about 22 by 36 centimeters) [term: ruled paper]
[Term] The other is graph or grid paper.
This latter one can be looseleaf or in a notebook. The first only comes as a pad or tablet.