The letter prefixes usually indicate one of two things.
Either who made that part, or who first put it onto the market. Semiconductor devices are like generic prescription drugs. The big company who invents the part only sells it while it's new, and will license out production to a low-cost producer when it stops being new.
In this case "IRF" is a prefix used by International Rectifier Corp. They first developed power MOSFET transistors sold with that three-letter prefix. But that was so long ago that a dozen or more licensed second-source factories also make that part.
The prefix "ERF" refers to the head honcho of Magnum/Palomar companies Eric Lewis. "E" as in Eric. His company that marketed the ERF parts was originally "EKL" his initials. But when his dad died, he took over and consolidated multiple name brands under the name "Palomar".
Semiconductor devices tend to come with one of two kinds of ID marking.
The first is "registered", so that it's coordinated with an independent industry association. In the USA it's "JEDEC", or Joint Electron Device Engineering Council. That sort of type number begins with a numeral, not a letter as a rule usually followed by the letter "N". A "1N60" is a diode that was made by dozens of companies over many decades. The 2N2222 is a small transistor made by many second sources since the middle 1960s. Japan has a similar setup they call "EIAJ" for Electronics Industry Association of Japan. They use a numeral followed by the letter "S", then followed by another letter to tell you what sort of device it is, then the numbers. A "2SC1969" is a NPN junction transistor meant for high (higher than audio) frequency circuits. A "1S88" is a small glass diode.
The second kind of marking is proprietary. This used to be most common for integrated circuit components with six, eight or more leads or pins. The usual format for a proprietary part number is one or more letters followed by digits.
General Electric made transistors and other semiconductors decades ago. Would use the single letter "D" followed by digits for their power transistors. Motorola always began the letter prefix of a part number with the letter "M".
Texas Instruments was in the transistor business back then, and sold parts with numbers the started with the letters "TIP". Story is this meant "Texas Instruments Plastic", back when power transistors had to be built into a metal housing. Making them from molded plastic was a major price breakthrough because of the labor it saved.
In 1967 or so. But the TIP-prefixed part numbers have since been made by dozens of other vendors since them.
Other manufacturers choose their own letter prefixes, and may or may not succeed in licensing those to be made by second sources later on.
It's not a complete free-for-all, just looks like it.
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