BSD 3-clause许可证和MIT许可证之间的主要区别在于第三条款（clause）。虽然这两个许可证都允许在商业和非商业用途中自由使用、复制、修改和分发软件，并且都不提供任何担保，但BSD 3-clause许可证要求在软件的发布中包含原始软件的版权、许可证和声明信息，而MIT许可证则不要求这样做。
具体来说，BSD 3-clause许可证的第三条款要求将以下信息包含在软件发布中：
Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met:
- Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer.
- Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution.
- Neither the name of the copyright holder nor the names of its contributors may be used to endorse or promote products derived from this software without specific prior written permission.
而MIT许可证只需要包含以下简单的声明：
Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:
The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.
因此，BSD 3-clause许可证更加严格一些，但也更具保护版权的作用。而MIT许可证则更加灵活，适用于更广泛的应用场景。