A mobile mechanic repairs your vehicle on-site, while a tow truck transports a broken-down vehicle to a repair shop — a mobile mechanic can often save you the cost and wait of a tow entirely for repairs that don't require a shop environment.
When a mobile mechanic can replace a tow
If the issue is something a mobile mechanic can diagnose and fix on-site — a dead battery, a bad starter, a brake job, a simple electrical fault — calling a mobile mechanic instead of a tow truck skips the step of moving the car entirely. That usually means faster turnaround and lower total cost, since you're not paying for both a tow and a shop's labor rate.
When you still need a tow
Some problems genuinely require a shop's lift, specialized equipment, or a controlled environment — major engine or transmission work, for example. In those cases, a mobile mechanic may still be useful for an on-site diagnosis to confirm what's actually wrong before you pay for a tow to the right kind of shop.
The practical difference
A tow truck moves a vehicle; a mobile mechanic fixes it where it sits. For many common repairs, skipping the tow and going straight to a mobile mechanic is the faster, cheaper path — it's worth a quick call to find out if your specific issue qualifies before defaulting to a tow.