There are a few differences between keyboards and screen readers and Léonie Watson highlights of them:
When using the tab key, keyboard focus and screen reader focus are synchronised with each other. The rest of the time, screen reader users have an enormous range of commands at their disposal for reading and navigating content independently of keyboard focus. The commands vary between screen readers, but they all have one thing in common: they’re tied to different HTML elements.
This is also a good reminder that screen readers behave differently from one another. It’s worth doing some research to see how our sites work in all these environments. One thing is clear from this post though: writing semantic and concise HTML is the best way to improve accessibility for both users with keyboards and screen readers. For example, Scott O’Hara has this recent post on best practices using the tabindex attribute to ensure accessible navigation using the keyboard.