Suits size is chest based. S /R/L is length. Length of torso. Sleeve length can be adjusted if the difference isn't too huge.
Things like shoulders are more based on the suit. Some companies make wider shoulders. Some smaller.A one size change in suit doesn't tend to lead to a huge difference in the shoulder size.
Waist is governed in by the style of the jacket. In part by the drop. The tag will say what the drop is.
Normally suits are drop six. That means a 36 comes...