today, two-day

Today or today means this present day or calender date--
There will be a meeting today at 6 p.m.
Can you have this done today?

Today may also mean the current age or era--
Today many people do their shopping on the internet.

Two-day or two-day describes soemthing that exists or lasts for about 48 hours--
We took a two-day trip; we both wanted to stay longer, but we couldn't.
The extra cost for two-day shipping may be worth it if you're in a hurry.

Now that you know that, you can say--
"I needed my package today; that's why I paid for two-day shipping."

Note--"today's" describes something that belongs to this day or calender date--
Do you know today's date?
Is this today's schedule?
Not to be confused with "two days", meaning two ( 2 ) calender days or about 48 hours--
It will take two days for your package to arrive.
We will be home in two days.