Able-ism is a form of discrimination or prejudice against individuals with disabilities (mental, emotional, and/or physical). Able-ism maintains an assumption that people with physical and/or mental disabilities are not normal individuals. Examples of able-ism include inaccessible public buildings, inflexible height of tables and counters, unusable transportation systems, and segregated education.
From: Thompson, Sherwood. "Able-ism." In Encyclopedia of Diversity and Social Justice, edited by Sherwood Thompson. Rowman & Littlefield Publishers, 2014.
Universal Design is the design and composition of an environment so that it can be accessed, understood, and used by all people, regardless of their age, size, ability, or disability. An environment (or any building, product, or service in that environment) should be designed to meet the needs of all people who wish to use it. Universal design constitutes the equitable access to spaces, objects, environments, and services.
From: CIO: Council Operations. (2018). Universal design - What is it? https://www.cio.gov/2017/12/20/universal-design.html