Is there any difference between "nowadays" and "these days"?

Question

Answer

Very similar

Nowadays = the period of time that is happening now; any continuous stretch of time including the moment of speech.

These days = the period of time that is happening now or happened in the past

However, usage is different.  Using DancingBear's example,

"These days I HAVE BEEN too busy with work to write to you."
"Nowadays I AM too busy with work to write to you."

Answer

very similar meaning
nowadays = the present, the current days
these days = the current days

Answer

Although the meaning is similar, they are not always interchangeable in usage.  ("Nowadays" means "in these days.")  For example,   you could say, "These days I've been too busy with work to write to you." It would not be appropriate to use "'nowadays" in that context.   At least, it would not sound natural to me.

Answer

They're interchangeable / near synonyms.