Medical and Clinical Laboratory Technologists and Technicians : Occupational Outlook Handbook :...

An MLT (medical laboratory technician) usually has an associates degree and an MLS has a bachelors. An MLS gets to do more complex testing and can oversee and evaluate MLTs.

An MLT is a Medical Laboratory Technologist. They perform the ordered tests on the acquired specimen.
An MLS is a Medical Laboratory Specialist. They might collect the ordered specimen, and/or assist the technician run the required tests.
I was a specialist in the Air Force, and after. I was a chemo-phlebotomist. As a Cold War Veteran, between Nam and Shield/Storm, I was given the option to specialize. My instructor wanted to burst my ego bubble. On the day we learned phlebotomy, I got my partner, right away. My partner couldn't get a drop out of me. Being a regular blood donor, IKNEW where my veins were. So, I took the syringe from my partner, and to the horror of my classmates, drew blood from myself. My first day of ward duty, they gave me the Cancer Section. I got all my patients drawn, on the first time, EVERY time. In fact, in seven years of practice, I only missed five people. Two reasons it didn't bother me: 1) Those five people would die within 12 hours. And 2) Even the doctor couldn't get it. Originally, I was a 90490, but they came up with a new MOS...92490-Chemo-phlebotomist. I'd teach my craft to members of all branches. I got called to draw generals, visiting foreign dignitaries, and even the President, once. I got my DD-214 in January of 1982. Hope this helps.

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