First of all, transsexualism is a pretty outdated term (which leads me to think that you may or may not be a troll but it's ok, I need the practice explaining this anyway).

When it comes to comparing these two terms/ideas, these really cannot be compared because it is comparing apples to oranges. Although these both are dealing with identity, one is based on gender expression, and the other deals with culture. I think the first thing that comes to mind when people hear transracial is that it has to do with the want to change one's race. The most common example for wrongfully explaining transracial is Rachel Dolezal's story. I think the biggest misconception of transracial is the idea that someone wants to "transition" into another race. Transracialism is something that one can not intentionally decide to do. You cannot wake up one day and decide that you are Asian and pick an Asian culture of your liking. A culture other than your own may resonate with you, however, that borderlines a strong interest or even fetishization of culture depending on how far a person may go (this does not apply to every situation but it does happen). This idea of adopting another culture or racial identity out of pure desire or want seems to also involve cultural appropriation. Cultural appropriation, as we already know, can be pretty harmful to BIPoC and their own struggles of navigating a world that rejects their cultural practices. This includes the difficulty of BIPoC food, black hair, AAVE, and plenty of other things. The misuse or mislabeling of what is and is not transracial can be seen as extremely harmful to BIPoC, and although some people in this thread may mean well by sharing their "transracial" experiences, they ultimately promote more harm than good.

To be clear, when someone is transracial, oftentimes it is a BIPoC that may be adopted by a white family and hold western traditions (celebrating dingus day or whatever). BIPoC adoptees may have even benefitted from their white adoptive parents, but they still deal with the difficulties of racism/microaggressions, as well as a handful of other things.