I was looking at these two examples and I was curious what the difference is between JCheckBox and JCheckBoxMenuItem.

http://www.macs.hw.ac.uk/cs/java-swing-guidebook/?name=JMenuBar&page=3
https://docs.oracle.com/javase/tutorial/displayCode.html?code=https://docs.oracle.com/javase/tutorial/uiswing/examples/components/CheckBoxDemoProject/src/components/CheckBoxDemo.java

These pictures make it look they are the same except JCheckBox is not in a menu but it is easy to add to a menu with the menu_name.add(menu_item) command. Is that correct?

http://www.javaperspective.com/menus.html
http://www.tutorialspoint.com/swing/swing_jcheckbox.htm

JCheckBox is for in any Panel or JFrame, JCheckBoxMenuItem is specifically for when you want a JCheckBox in a menu.

Will I get any weird errors with using JCheckBox in a menu? I have done that and it seems to be working.

if you have done it, you know the answer to your question.