Difference between the new Salesforce Platform Developer 1 certificate and the old Developer certification DEV-401

You may like to watch following video.

https://www.youtube.com/watch?t=3&v=wM5Th-ComR4

AppBuilder Transition Certification focus on declarative skills. It do not focus on Visualforce at all now. It do focus on Lightning Introduction, Salesforce1 understanding, Sandbox and Packages.

Platform Developer 1 focus on coding skills. It also focus on Introduction to Lightning.

There is no prerequisite for Platform Developer 1 certification now unlike DEV 501 for which we had to be certified developer was prerequisite.

Platform Developer 2 focus on advanced coding skills and also has assignment.It also focus on Integration skills(SOAP API, REST API, Analytics API) now which were not tested earlier in Advanced Developer certification.

Developer 401 is succeeded by App Builder. Developer 501 is succeeded by two exams namely Platform Developer 1 and Platform Developer 2.

If you hold Developer 401, you can take a transition exam and get the App Builder certification.

If you hold Developer 501, you can take transition exams of Platform Developer 1 and 2.

Hope it clarifies your confusion.

The Dev 401 certification doesn't test any of the Apex and Visualforce skills but the name says a Certified Force.com Developer. So now salesforce made the changes to this developer certification so that the Platform developer I certification test basic knowledge on Apex,Visualforce,Lightning. Where as the configuration skills is certified as Platform App Builder.

The topics for both the Platform Developer I and II certification is almost similar but the developer II is advanced and you need a good experience in coding and also has the programming assignment followed by essay exam.