Accessibility features in Adobe Acrobat DC and Adobe Acrobat Reader DC fall into two broad categories:

Features that make the reading of PDF documents more accessible.
Features that help create accessible PDF documents. To create accessible PDF documents, you must use Acrobat Pro.

Features to support the reading of PDFs for people with disabilities

All versions of Adobe Acrobat DC, Adobe Acrobat Reader DC, Acrobat Standard DC, and Acrobat Pro DC provide support for the accessible reading of PDF files by persons with disabilities:

Preferences and commands to optimize output for assistive technology software and devices, such as saving as accessible text for a Braille printer.
Preferences and commands to make navigation of PDFs more accessible, such as automatic scrolling and opening PDFs to the last page read.
An Accessibility Setup Assistant Wizard for a walkthrough in accessibility formatting
Keyboard alternatives to mouse actions.
Reflow capability to temporarily present the text of a PDF in a single, easy-to-read column.
Read Out Loud text-to-speech conversion.
Support for screen readers and screen magnifiers
Support for high contrast and alternative foreground and background colors

Features to support the creation of accessible PDFs

Acrobat Standard provides some functionality for making existing PDFs accessible. Acrobat Pro must be used to perform most tasks — such as editing reading order or editing document structure tags — that are necessary to make PDF documents and forms accessible (For more information see Comparison of Accessibility Features in Adobe Acrobat DC Plans).

Creation of tagged PDFs from authoring applications
Conversion of untagged PDFs to tagged PDFs from within Acrobat
Security settings that allow screen readers to access text while preventing users from copying, printing, editing and extracting text.
Ability to add text to scanned pages to improve accessibility
Tools for editing reading order and document structure
Tools for creating accessible PDF forms
Ability to set document properties including title and expose them through the title bar of the application