El Rio Del Tiempo is the attraction located in the Mexico pavilion at Epcot which was adapted to become Gran Fiesta Tour with the Three Caballeros.
I have only ridden the Caballero version of this ride so have relied on Youtube on-ride videos to get an idea of how this attraction started out.
The loading area and first part of the river are unchanged from the original attraction, with the sole exception that the Three Caballeros portraits are not on the wall of the loading area. As guest sail into the first tunnel, they are taken back to ancient times in Mexico. The screens show warriors and ancient tribesmen performing dances, fights and other rituals. These are live action sequences rather than animation.
Guests then sail into the town celebration, just as in the Caballero version with the 'Small World-style' figures playing music and dancing and the skeleton mariachi band standing on a bridge over the river. The one significant difference in this scene is the lack of a Donald Duck pinata, with the children in that section playing with an ordinary pinata.
Guests then view more screens, one of which clearly shows the same film sequence of a speed boat that Donald has been inserted into in the Gran Fiesta Tour. All the screens here are identically placed and feature very similar footage to that which features the Three Caballeros.
There is a slight shift in the next section which, in Gran Fiesta Tour sees further fiesta celebration but in El Rio Del Tiempo sees various merchants attempting to sell their wares to the passing guests. This again is live action footage shown on the screens.
Guests float on to the firework scene familiar from Gran Fiesta Tour, although this section also features a colourful carousel on which spin various marionettes (these are, interestingly, more 'life-like and in proportion than the 'Small World-style' figures from earlier in the ride). Passing on to the end of the ride guest see a different map to the one now present in Gran Fiesta Tour.
Maybe it's unfair of me to make a judgement not having ridden the original, but I definitely prefer Gran Fiesta Tour to El Rio Del Tiempo. The addition of the Three Caballeros adds vibrancy to a ride which, to be honest, feels a little lacklustre in without them.