The thing I’ve always been wondering about CFLs is about why they never looked like a linear fluorescent tube in color or even in light pattern (CFLs produced harsher shadows, similar shadows to a standard snow cone LED or a soft white incandescent). The light color also never matched a linear fluorescent tube, which I find interesting. Warm white CFLs don’t look like warm white fluorescents, even daylight CFLs don’t look like daylight fluorescent tubes. The 2700K CFLs seem to have a more noticeable fluorescent hue than the 5000K counterparts (which is pretty ironic). Some of the soft white CFLs had a noticeable pinkish hue or an abnormally yellow tint that just isn’t seen on LEDs, and that pinkish hue is also sometimes seen on warm white fluorescent tubes.

Instead, a warm white CFL looks almost like a cheaper warm white LED at full brightness (if it’s a higher quality model). A daylight (5000K) CFL looks like a 5000K LED. 5000K LEDs used to be bluer than the CFL counterparts but newer 5000K LEDs seem to match the older 5000K CFLs better.

Maybe a smaller tube makes the light and phosphor more concentrated? Don’t know. But, when I see a daylight CFL in a light with an opaque enclosure on it, I do not assume CFL at first glance, I’ll assume it is an LED unless I look at the bulb, or if I turn it off, and see it warm up. Those are my only ways to tell. If there are actually daylight CFLs in globes I cannot turn off then I’ll just assume it’s an LED the whole time. A linear 5000K tube, on the other hand, does have a true fluorescent look, both T8 and T12. 5000K tubes are also more of a pure white while 5000K LEDs and CFLs have kind of a hit of blue.

Many lower quality LEDs have a very similar to light quality and color to CFLs (if the CFL is at full brightness). 4100K CFLs look more like 4100K LEDs than 4100K fluorescent tubes.

Some of the 2700K CFLs, especially cheap or early models, have fluorescent casts to them though, such as a pinkish color. The early TCP’s (the ones branded n:vision and commercial electric) had a very yellowish color that looked very much fluorescent. Some of the older GE’s also had an abysmal yellow color to them.

Well, in my understanding CFLs run at much higher current densities in the discharge column compared to thick linear tubes in T8/T12. That favors a bit more of visible light emitted by mercury discharge compared to its UV output. So resulting tint of combined light, mercury + phosphor, shifts a bit to blue-green compared to the same phosphor mix in T8/T12, until specially compensated in the mix. That is particularly noticeable in high power GX24 CFLs in 26 or more watts, that push T12-scale current of 320mA into tiny arctubes of circa T4 size.

Also, CFLs are practically never made with wideband halophosphate mixes (they won't last for long) and rare earth phosphor light might look a bit harsh due to large dead gaps in the spectrum (household 827 color is especially bad in this regard unfortunately). 2700-3000K LEDs fix this for large, by the way.

There is not much technical reason why a CFL can not be made the same color as the linear fluorescents, but the main difference is the target market and consequently the use case and engineering optimization targets.

CFLs were targeted as incandescent replacenments for homes, so targeted very dense lumen packages (small size for the light output) and lower overal light flux (around 1000 lm and below per lamp), strong push for low unity sale price but with less strict requirements for efficacy.
Linear fluorescents were targeted for commercial market, so there the total cost of light became the driving force, so efficacy and long life/high reliability were the prime driving forces, as those form the majority of the total cost of the light. Then most applications were less strict about the color quality.
So the design target were rather large, high efficiency lumen packages (like F36T8/F32T8 with their 3000lm per lamp ballpark), with phosphor mixes barely meeting the CRI limits but boosting the lumens as high as possible (therefore the stronger green components), often barely reaching the 80 CRI (and not speaking about questionable quality super-low-cost makers).
All that beside the color rating category could be equal.

Yes, this difference is not absolute, but definitely driving the design of the mainstream products for the given market.

I have an EOL 15W daylight halophosphate CFL in my father home. Despite lasting very long, it considerably dimmed out, due to phosphor degradation.