Hello, Ei Shwe Zin. The two vary in degree of cleanliness, when comparing the terms to a literal sense. Perfectly clean means without any residue left; it’s perfect. Very clean would mean the cleaning was great, but could still be better. But with all that said, when using both terms without the literal meaning, both can be used interchangeably. For example: “The house was perfectly clean.” “The house was very clean.” These two would give off the same meaning. I hope this helps. Cheers!

For example, cleaning the house or apartment. The person living there would try to make their home “perfectly clean” is they were expecting important visitors. Another common way to say this is “spotless” (for example: “Look at their home, it is spotless”). A “very clean” home is organized with few things out of place, but it’s not perfect per say.

Mostly it's just a stylistic choice. But in some cases "perfectly clean" means something like "literally perfect clean", something specific. While "very clean" simply means "it is really clean", or not as specific.