There are many names for having attraction to multiple genders. They may have very similar meanings but the differences matter to the people who choose these labels and that is enough to make them valid on their own. These also apply to all the romantic variations of the labels. So what are all of these labels?
This is the one you're most likely to have heard of, as it is the label that has been around the longest. Bisexuality has always included Nonbinary people, however it is commonly known as the capacity for attraction to both men and women - because bi means two (see: bicycle having two wheels). Now, it roughly means attraction to your own gender and other genders. What do I mean by roughly? Everyone kind of has their own definition and what one bi person tells you the definition is may differ slightly from another's, and all of these are completely valid. Bisexual people sometimes describe their attraction to individual genders as feeling different for each gender, for example attraction to girls could feel like 'ooo' where attraction to guys could feel like 'aaa'.
Bisexual people can also have preferences for genders. Even if a person has an overwhelmingly feminine aliged attraction and a very small amount of attraction to masculinity, they are still bisexual.
Some bisexual people use percentages to descirbe their attractions (eg. 70% into women or femininity, 25% into men or masculinity, 5% into nonbinary people or androgyny), however not all bisexual people use this, and do not assume they will.
Visit https://bi.org/en for more info.
This simply means the capacity for attraction to all genders (Pan meaning 'all' in Greek). Pansexual people sometimes describe all of their attractions to different genders feeling the same (which can sometimes lead to people not realising until later that they're asexual!). Some people may choose the label simply because they like the flag's colours!
Omnisexuality (Omni meaning 'all' in Latin) is similar to Pansexuality in that it means attraction to all genders, but it is similar to bisexuality in that attraction to different genders can feel differently.
Not to be confused with Polyamory, the definition for this one is merely attraction to multiple genders, however not necessarily all genders (poly meaning 'multiple' in Latin). A Polysexual person may not be attracted to men specifically but attracted to all other genders.
There are many misconceptions when it comes to attraction to multiple genders. One of the main one is that these people are 'greedy', more promiscuous, or more likely to cheat. These are all absolutely untrue. Just because a person has the capacity to be attracted to more than one gender, this does not automatically mean that they will cheat in any way. They fall in love just as anyone else.
One of the most important things to remember is that the person with multiple attractions is NOT straight when with a person of the 'opposite' gender and they are NOT gay when they are with the 'same' gender. Neither are they half straight or half gay - they are the sexuality with which they identify.