Convert tnef to msg

What is the difference between .tnef and .msg?

Description: File generated by Microsoft Exchange email programs such as Outlook; appears as an email attachment for email clients that don't recognize Microsoft's proprietary TNEF format; may cause the text "application/ms-tnef" to appear in the email if the email client does not recognize Microsoft Exchange formatting.; An MSG file is an email message, contact, appointment, or task created or saved within Microsoft Outlook. It may contain one or more email fields, which includes the date, sender, recipient, subject, and message body, or contact information, appointment details, and one or more task descriptions. MSG files are also compatible with other programs that use Microsoft's Messaging Applications Programming Interface (MAPI).