Differences between .ContextMenu and .ContextMenuStrip

http://www.informit.com/articles/article.aspx?p=606224&seqNum=2

You might wonder why Microsoft has replaced a valuable and popular
control with a newcomer. The ContextMenuStrip control takes a good
idea and makes it better. It works just like the ContextMenu control.
You still attach a ContextMenuStrip control to another user control by
changing that control’s ContextMenuStrip property. However, Microsoft
has substantially improved the features you can add to a
ContextMenuStrip cont…

Look at the examples at MSDN:

http://msdn.microsoft.com/en-us/library/system.windows.forms.contextmenustrip.aspx

ContextMenuStrip replaces ContextMenu. You can associate a
ContextMenuStrip with any control, and a right mouse click
automatically displays the shortcut menu. You can show a
ContextMenuStrip programmatically by using the Show method.
ContextMenuStrip supports cancelable Opening and Closing events to
handle dynamic population and multiple-click scenarios.
ContextMenuStrip supports images, menu-item check state, text, access
keys, shortcuts, and cascading menus.

http://msdn.microsoft.com/en-us/library/system.windows.forms.control.contextmenustrip.aspx

If a ContextMenu has also been assigned to the control, the
ContextMenu takes precedence over the ContextMenuStrip.