It is most similar to the 3-clause BSD license, which is essentially different only in the fact that it contains a notice prohibiting the use of the name of the copyright holder in promotion. The 4-clause BSD license also includes a clause requiring all advertising of the software to display a notice; the MIT License has never had this clause. The MIT license, however, more explicitly states the rights given to the end-user, including the right to use, copy, modify, merge, publish, distribute, sublicense, and/or sell the software.
According to the Free Software Foundation's license list, the MIT license is more accurately called the X11 license, because MIT has many licenses for software. However, the Open Source Initiative refers to it as the MIT License, as do many other groups.
Because the MIT License is not copyrighted, other groups can elect to modify the MIT License to suit their own needs. For example, the Free Software Foundation uses a license identical to the MIT License for its ncurses library, except for the addition of this text:
Adding text like this makes the license almost identical to the BSD license.
Except as contained in this notice, the name(s) of the above copyright holders shall not be used in advertising or otherwise to promote the sale, use or other dealings in this Software without prior written authorization.
Still other groups prefer to dual-license their products under the MIT license; an example of this is older versions of the cURL library, which allowed you to choose either the Mozilla Public License or the MIT License.