When discussing the differences between racial or cultural subcultures, it is important to remain culturally sensitive. The word "Chicano," for example, was considered derogatory when it first appeared, but later generations of Mexican-Americans have since deemed it acceptable. Brazilians may be considered to be Latino, but are not considered Hispanic. This is why it is important to understand the difference between the three words commonly used to describe those of Spanish or Mexican descent.
The most straightforward of the three cultural identifiers may be the word Chicano. "Chicano" refers specifically to Mexican-Americans, or anyone else of Mexican heritage. When Mexican workers and their families first moved into the United States, they were often referred to as "Mexicanos," which became shortened over time to "Xicanos" or "Chicanos". At first, "Chicano" was considered to be derogatory, somewhat akin to "Chinaman" or "Negro." Eventually, however, many in the Mexican-American community embraced the term, at least informally. There are still older Mexican-Americans who view "Chicano" as something less than respectful. It should only be used to describe those of Mexican descent, not those of Central or South American descent.
The word "Hispanic" is a bit more universal than "Chicano." Historically, areas conquered by the Spaniards were considered part of a region originally called Hispania. Modern countries which can trace their history to Spain are now considered to be Hispanic, and include Mexico, Central America, and most of South America where Spanish is the primary language. The only exception to this Hispanic designation is Brazil, which was settled by Portugal, not Spain. Any citizen of those countries originally colonized by Spain can be considered Hispanic. People from Mexico, El Salvador, Guatemala, Panama and other areas south of the American border would all be considered Hispanic.
"Latino" is very close in meaning to Hispanic, but it also includes other countries such as Brazil. The regional description "Latin America" now refers to the countries where Romance languages (Spanish, Portuguese) are spoken, but was originally used by Napoleon to describe other Romance speaking (French included) territories throughout the Americas. To be described as a Latino is not considered derogatory, although it can be construed as a generic for all Hispanic cultures, much like referring to a Korean or Japanese-American as "Asian." While "Latino" may be politically and socially correct, it may be more culturally sensitive to learn a person's specific heritage and refer to him or her as "Nicaraguan" or "Guatemalan" rather than using the broader term, "Latino."