Data Science
Data scientists primarily fetch data, build and maintain databases. They clean, segregate and compartmentalize data available to cater to different needs, along with working on data visualization and its analysis. It is mandatory to get a certification as there is a diverse set of profiles that require specialised expertise to land a job in this field. The overall scope of data scientists tends to be lower as compared to big data owing to the individual profiles which come within the ambit of data science.

AI and ML
Artificial intelligence (AI) is basically an area of computer science which deals with the creation of intelligent machines that act, react and work like humans, while machine learning (ML) is an application of AI that lends the system the ability to learn, understand and improve from experience without having to programme it automatically.
Certifications in AI & ML will help candidates gain the essential know-how, concepts, and skills that are needed to develop effective AI systems, comprehend the challenges being posed by AI in workspaces, and several other relevant functions that will enable candidates to secure good job roles in the industry as a machine learning engineer, AI engineer or data scientist.
