What exactly is the difference between a Master Sergeant and a 1st Sergeant? Is one technically higher than the other?

One is in directly in charge of a company of soldiers 1SG, the other is normally in a operational role, MSG.

MSG is normally a senior NCO in a technical MOS.
1SG is normally THEE senior NCO at company level.
Don’t piss off either one!

As stated, Google and chain of command. Will your next question ask the difference between CSM and SGM?

As a company commander ( 3 companies in and out of combat) my First Sergeant was my sounding board, confidant, heart on all matters concerning my soldiers and NCOs. He had insight and experience that I could rely on and could function as an executive officer when necessary. My platoon leaders, no matter how smart, brave and dedicated were always in a training mode and when they got really good they moved up and out. That is how the system works and how we can get good commanders. The First Sergeant and NCOs provide the continuity and experience essential for success. A MSG gives an administrative, staff, technical operation a depth of experience and operational continuity necessary for success. Equally capable individuals but the First Sergeant is part of the command structure as is the CSM

A MSG is a staff position / support for command jobs at the BN , BDE , division level and a 1SG is a command position in charge of troop that do direct contact or maneuver in the field with fighting bad guys ..

1SGT out ranks Master SGT

A MSG. Is a technically orientated NCO. Where as a First Sargeant's mission is to make sure that the commander's intent is carried out, and at the same time be a voice for the enlisted personnel under his command

This has been answered fairly......in other terms, compare a SPC with a CPL.

1SG is the senior nco and advisor to the Company Commander and a part of the command staff at the Company level. He/She is lateraly promoted from MSG to1SG. MSG usually works at staff level Battalion or higher.

I served as a First Sergeant as an E7 and earned my “M”
Identifier. It’s a duty position and you don’t have to be a E8. That’s why I believe the Army should have an E7 stripe with a diamond as the AF does.