The type of reggae that Marley played is 'roots reggae' and is just one of many styles of music which came out of Jamaica.
Because of American influence, it tends to be based on standard rock quartet electric instruments, with the addition of very subtle touches from steel drum, kalimba, and other percussion instruments.
In the classic incarnation of the Wailers (which is the one which played many of the Marley hits you're familiar with) the line-up was:
Bob Marley (vocals, guitar, percussion)
Peter Tosh (vocals, guitar, piano, organ)
Tyrone Downie (vocals, keyboards, percussion)
Bunny Wailer (vocals and percussion)
Guest horn musicians and backing vocals were sometimes added.
The distinctive 'beat' of pure reggae is known as 'The Drop'; it is generated by a very strict pattern of regular 4/4 time downstrokes on a guitar, often played 'up the neck' rather than at first position. A bass drum may be used to accentuate the third beat of each measure.
The equivalent in ska music is called 'The Skank', very similar to the drop but much more frenetic (though no less regular.)
Roots reggae puts a premium on the skills of the rhythm guitarist and the bass player to maintain a rock-steady drop.
Other styles of music from Jamaica, like dub, rely on sampling and electronics much more than classic roots reggae. Try Lee 'Scratch' Perry if you want a taste of this.
A brief overview of how genres of reggae fit together is given by Wiki below.
Hope that helps.
PS - try www.bobmarley.com, it's comprehensive & has links also.