The phrase "actually three types of" is correct and usable in written English.
It can be used when clarifying or specifying the number of categories or classifications in a discussion or explanation.
Example: "In our research, we found that there are actually three types of renewable energy sources: solar, wind, and hydro."
Alternatives: "specifically three kinds of" or "in fact three categories of".
There are actually three types of placenta accreta, although the term is commonly used to describe all of them.
According to science reporter and psychologist Daniel Goleman (the man who popularized the theory of emotional intelligence), there are actually three types of empathy that operate in different areas of the brain.
There are actually three types of basic push up variations that use different muscles.
As shown in Figures 1 and 2, there are actually two types of spectrum holes.
But there are actually two types of GDH: the one coded by GLUD2, which is found mostly in nerve tissues, and a second type, coded by a gene called GLUD1, which is found in many different cells and performs a variety of functions.
There are actually two types of holograms in wide use today, and no, the "Tupac hologram" doesn't count.
Probing questions from Oppenheimer prompted Robert Marshak's innovative two-meson hypothesis: that there were actually two types of mesons, pions and muons.
After pouring more research and thought into the topic than I care to disclose, I've developed the theory that there are actually two types of hipsters, and they are both totally legitimate and sort of uniquely hateable.
I call these UMLACAs unidentified munitions linked to alleged chemical attacks—and there are actually two types of UMLACAs, a high explosive type and another type loaded with an unknown substance that only appears at the sites of alleged chemical attacks.
In his work on transsexualism, Blanchard argued that there are actually two types of MTF transsexuals, with autogynephiles being one type and "homosexual transsexuals" being the other.
At medical schools and the majority of general hospitals, there are actually two types of ECs [ 23]: an EC that reviews and monitors drug clinical trials called a chiken-shinsa-iinkai (clinical trial review committee), and an EC that reviews protocols from researchers affiliated with the institution called a rinri-iinkai (ethics committee).
