It would be both nice and convenient if the answer to the question of whether or not we are equal were a simple "yes." However, that will not stand up to scrutiny, even to the most liberal of minds. Ultimately, the answer is "no," we are not equal except that we each are only one person. Once we get beyond that similarity, the differences begin indiscriminately.
Sometimes, though, the differences are discriminatory. We would all like to think that we are either exempt from the possibility of discrimination, or that our discrimination is more justifiable than other discriminations, but it is still discrimination.
There is truth in measuring things in degrees or in amounts, and some discrimination is more justifiable than other discriminations. To wit: it is more justifiable to discriminate against people with disabilities if the disability means they cannot fulfill the needs for the job, like lifting or climbing requirements, than it is to discriminate against them because they don't fit the image of the company.