The main difference between LAMP and MEAN stacks is that the LAMP stack uses Linux, Apache, MySQL, and PHP, while the MEAN stack uses MongoDB, Express.js, AngularJS, and Node.js.
Both stacks are free and open-source software (FOSS) developed for use in web development. The LAMP stack has been around for much longer than the MEAN stack; it was first introduced in 1998, while the MEAN stack was introduced in 2013.
Moreover, LAMP uses a relational database management system (MySQL), while MEAN uses a NoSQL document-oriented database system (MongoDB).
Other differences include the programming languages used: PHP vs. JavaScript. Finally, LAMP is more prevalent among web developers because of its long history and the number of tutorials & articles available online. MEAN is newer but has been growing in popularity due to its advantages in terms of scalability and performance.