The definitions below courtesy of www.latinbayarea.com
Salsa is a term of unclear origin that emerged and became popular in New York in the late 1960s. It has remained controversial since. For some, salsa is nothing more than a marketing handle for Afro-Cuban music as updated and reinterpreted by Latinos in New York. Others hear it as a distinctive New York-Caribbean style, pointing out the grittier sound and the pan-Latin elements (e.g.: Puerto Rican, Panamanian and Dominican as well as Afro-Cuban), along with R&B and jazz influences.
While there are similarly named dances in other countries, this merengue, a fast-paced music danced in a tight two-step, is the national dance of the Dominican Republic. Born in the Dominican countryside in the 19th century of African and European traditions, merengue was traditionally played by small groups featuring accordion, güiro (metal scraper) and the two-headed tambora drum. It became enormously popular in the 1980s played by brassy, big band-like orchestras.
The Latin GRAMMYs' "Traditional" field celebrates classic Creole styles and the Cuban son is an essential, subtle blending of African and European elements developed in the island's Oriente (Eastern) province. Rich and malleable, son is to Cuban popular music what blues is to Afro-American popular music. Much of what is known as salsa, for example, is based on son.
Cumbia, a sweetly syncopated dance music from the Atlantic coast of Colombia, is a classic example of the Creole fusion of indigenous, European and African cultural elements in the Americas. The original cumbia featured percussion and voice but as it evolved, instruments were added. By the time it reached Colombia's urban centers, in the 1940s, it was played by large dance orchestras. Cumbia has reached far and wide, but has been especially influential in Mexico and Central America.
The dramatic ranchera, which emerged during the Mexican Revolution, is considered by many the country's quintessential popular music genre. Sung to different beats including the waltz and the bolero, its lyrics traditionally celebrate rural life, talk about unrequited love and tell of the struggles of Mexico's Everyman. Tejano/conjunto and norteño acts favor rancheras with romantic themes played to a polka beat. Mariachis and grupos prefer the gentler boleros and waltzes.
Banda, literally "band" in Spanish, generally refers to the large brass-heavy ensembles that first appeared in the northern Mexican state of Sinaloa in the early 20th century. Early banda featured trumpets, trombones, tubas and percussion instruments, but no lead singer. The contemporary banda, although it still features a horn section, often includes keyboards and electric bass. Banda music exploded in the '90s due to the rise of la quebradita, a fast dance that incorporates moves from polka, rock and roll, and cumbia.
The term "grupo," which literally refers to a band of musicians, in recent years has come to denote keyboard-driven romantic pop bands with members who share equal billing. Grupo music is referred to as "onda grupera."
Tejano, Spanish for "Texan," is a hybrid of traditional Mexican rancheras, polkas and cumbias infused with elements of country, blues and pop. Bandleader and saxophonist Isidro "El Indio" López is credited with creating modern Tejano music in the late 1950s by bringing together the sounds of the big band Tejano orchestra and the accordion-centered conjunto. By the '90s, Tejano had blossomed into many sub-genres including Tejano/pop, Tejano/R&B and Tejano/country.
Conjunto is a unique Texas-based music tradition born in the 19th century that continues to evolve and thrive today. Conjunto, like jazz, blues, and rock and roll, is a distinct American musical genre that has had a major impact on the Mexican American community of the United States, as well as reviving an interest in the accordion, and is gaining fans around the world. Accordion-driven conjunto is its own culture, fans and followers, and plays an integral and vital role in many communities. It is dramatic, vibrant and sensual - far from traditional! Flaco Jimenez is an example of the conjunto sound.
Norteño, Spanish for "northern," is a genre rooted in rural folk music but enriched by many elements from the music of German and Czech immigrants. A norteño band typically features an accordion and a bajo sexto (a 12-string bass guitar), but modern groups such as Los Tigres del Norte and Bronco also include electric bass, sax and keyboards.