From Wikipedia:

Ska (date of origin: 1950s)

Ska combined elements of Caribbean mento and calypso with American jazz and rhythm and blues. It is characterized by a walking bass line, accented with rhythms on the offbeat.

Instruments: Guitar, Bass guitar, Trumpet, Trombone, Saxophone, Piano, Drums, Organ

Reggae (date of origin: 1960s)

While sometimes used in a broader sense to refer to most types of Jamaican music, the term reggae more properly denotes a particular music style that originated following on the development of ska and rocksteady. Reggae is based on a rhythm style characterized by regular chops on the off-beat, known as the skank. The tempo is generally slower than that found in ska. Reggae usually has accents on the 3rd beat in each bar, there being four beats in a bar; many people think it's accentuated on the 2nd and 4th, because of the rhythm guitar.

Instruments: Bass - Drums - Guitar - Organ - Brass instrument - Melodica

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There you go. I hope this helped.