Omnisexuality is a sexual orientation where one is attracted to all genders or any gender, while having a preference. Often confused with pansexual, omnisexual does have attractions to any and all gender but with a certain preference. Pansexual is attraction to any and all gender without preference.
"Pan-" comes from the Greek language and "Omni-" from Latin, both meaning "all" or "every." However, they differ from each other.
Omnisexual individuals will take gender into consideration, or at the very least, they could. With pansexual individuals, they often love regardless of gender, not taking it into consideration. Confusion can tie in where preference lies; some pansexuals have expressed consideration of gender, while some omnisexuals expressed genderblind attraction. In addition, Omni is often called a synonym to Pan, rather than a separate label, so many will say it is useless or the same as pansexual.
With Bisexuality, both are often compared due to Bisexuality's fluidity allowing sexual attraction to all genders to be possible, but Bisexuality isn't dependent on preference while Omnisexuality often is.
The following days of the year officially recognize Omnisexual and Omniromantic folks.
March 21th: Omnisexual awareness Day.
June 6th: Omnisexual and Omniromantic Pride and Visibility Day.