A "Texican," prior to 1836, was a person from Texas (then part of Mexico) of non-Mexican (i.e. non-Hispanic) ancestry,
usually someone who had been born in the United States (and usually a southerner) and had emigrated to Mexico's northernmost state.
A "Tejano" was, and is, a descendant of the original Spanish and Mexican families who settled the territory from about 1749 onward.
Both Texicans and Tejanos fought side by side in the Texas army that won independence from the dictatorship of Santa Anna.
In the context of the struggle for Texas independence, all were referred to as "Texicans."
Later, they were called "Texians" and finally, "Texans."
Ref: chris-horton blogspot, which is no longer active.