components within a triangle in an electronics diagram

The triangle is a symbol for a buffer, driver or amplifier, whatever you call it.

The transistors drawn inside the triangle are there to let you know what is the type of your output. Thanks to this drawing you can see that the outputs are switched via BJTs between the power supply rails using some kind of Push-Pull topology.

Knowledge about the type of output is useful. If those were power MOSFETs, you would expect them to exhibit different behavior than BJTs. A BJT will have a voltage drop whereas a MOSFET will have a resistance between drain and source.

The drawing doesn't provide the exact schematic for the amp/buffer and it doesn't have to. The exact schematic would be a lot more complicated and this image is there to clarify things, not complicate them.

So, in short, the triangle symbolizes your driver/buffer and the transistors are there to let you know that the output was made using bipolar transistors.

That is just a notation, not by any means a schematic. The "triangles" themselves symbolise high current drivers, the two "transistors" drawn there are just to symbolise what the circuit is doing. There more components "inside the triangle", that for sake of brevity are not displayed.

This is similar to pseudocode and real source code in a given programming language. This is a "pseudo-schematic" of the chip.

BTW: Why do you want to get to know what's inside the IC? Would you like to get higher current output, because the chip itself could not drive the motor you want to use?

A triangle with one input and one output usually represents a buffer: it copies its input to its output, usually at a greater signal strength, usually cleaning up the input signal to logic 0 or 1.

Those transistors are probably exactly what the output stage looks like: a PNP transistor connected to the power line and an NPN connected to ground, only one of which is on at once.

A triangle with two inputs and one output usually represents an op-amp.