Both Udemy and edX offer online courses and provide certificates upon completion, but there are some differences between the two platforms.

1. Course Selection: Udemy has a vast library of courses across a wide range of subjects, including technology, business, arts, and more. It features a larger number of courses compared to edX. edX, on the other hand, focuses more on courses from universities and educational institutions, offering a variety of subjects including computer science, data science, humanities, and more.

1. Course Quality: The quality of courses can vary on both platforms. Udemy allows anyone to create and sell courses, which means the content quality can vary greatly depending on the instructor. On edX, courses are developed in collaboration with renowned universities and institutions, ensuring a higher level of quality and academic rigor.

1. Credibility and Recognition: edX certificates are often more recognized and valued by employers and academic institutions due to its partnerships with prestigious universities. Udemy certificates, while still providing proof of completion, may not carry the same level of recognition.

1. Pricing: Udemy courses are generally more affordable and often go on sale, with frequent discounts and promotions. edX offers a mix of free courses (with the option to pay for a certificate) and paid courses, usually at a higher price point.

Ultimately, the choice between Udemy and edX certificates depends on your specific needs and goals. If you are looking for a wide variety of courses at an affordable price, Udemy might be a good fit. However, if you are seeking high-quality courses from renowned institutions and want certificates with greater credibility, edX could be a better option.