main.yml (tasks)

- name: Add all group1 users
  user: name={{ item.key }} group=group1 comment="{{ item.value.name }}" password="<REMOVED>" update_password=on_create shell=/bin/bash
  with_dict: group1
  register: group1_users
- name: Add all group2 users
  user: name={{ item.key }} group=group1 comment="{{ item.value.name }}" password="<REMOVED>" update_password=on_create shell=/bin/bash
  with_dict: group2
  register: group2_users  

main.yml (vars)

users: 
	group1: 
		user1: 
			name: Full Name
		user2: 
			name: Full Name
	group2: 
		user3: 
			name: Full Name