What is the difference between a op-amp comparator such as 741 and an actual comparator such as 111 ?

 

Operational Amplifiers generally are built to work in the linear range of operation, using feedback to control gain of an analog signal. Applications such as mixers, preamplifiers, etc.

Comparators are optimized for switching speed and "rail to rail" output, where the output voltage is either the positive supply voltage or negative supply voltage/ground, with little time in between those two states.

 

Adding to thatoneguy's info,
Opamps generally can both source and sink current.
Comparators generally can only sink current. If an output current source is required, one needs to select a "pull-up resistor" to provide that current.

Opamps are not really designed to be operated in "open loop" mode (no feedback); if one attempts to use an opamp as a comparator, the output of the opamp will be in constant saturation, causing a good deal of heat.

Comparators were designed to be operated in open loop mode.