Fluorescent bulbs that work in a regular "A" base socket are not considered "low voltage". They require the same voltage to operate as a standard bulb. The cost savings occurs after using 120 volts as source voltage, what they are actually is "low wattage". That being said, Line Voltage Lighting fixtures use 1 of the standard voltages supplied by the power company(usually 120 for residential-120 or 277 for commercial-240 or 208 could also be used, but are uncommon.). Low Voltage Lighting fixtures use voltages below 50 volts . This is usually accomplished by using a step down transformer. 12 volts is the most commonly used for lighting. Each type of lighting has lamps(bulbs) designed for that particular voltage with the exception of flourescent lighting which have voltage specific ballasts. Just because a fixture has an A base doesn't mean it is line voltage. 12 volt A base bulbs are readily available and used. There are Line and Low voltage bi-pin lamps. You will have to check for documentation on the fixture(usually near the socket).
As far as operation is concerned, Line voltage lighting circuits can carry 1 fixture up to fixtures totaling max wattage of the circuit with no noticeable difference in light intensity between the fixtures or in total. With low voltage fixtures you will notice a difference from 1 light to the next, getting dimmer the farther it is from the transformer(unless you wire them in a closed loop). Even if wired in a closed loop, the more fixtures on the circuit the dimmer each light will be(if 1 fixture=bright, 3 fixtures =all medium bright, 7 fixtures=all dim. The only exception to this are LED Light Fixtures which at this time are very expensive
40 Years experience. Certified Journeyman Electrician with various specialty certifications including Landscape Lighting.