Workout x Physical Exercise: Qual a diferença?

Ok, there's an easy way to internalize this. Take a bunch of phrasal verbs and write out the two forms in single or double sentences:

A weekend is great because the week ends.

And so forth.

Wow, thanks. This is something of a minor visibility, but great importance.

Thaks for the tips.

As a general rule, think of splitting off the preposition when you're using it as a verb (often it's a phrasal verb, right?) and keeping them together (sometimes with a hyphen) when using it as a noun:

The plane's takeoff was a smooth one.
Planes take off smoothly in calm weather.

The playoff is tomorrow.
They play off tomorrow.

In more unusual noun forms, a hyphen can really help:

The call-up involved all under-21's.
All under-21's were called up.

I'm generalizing, of course. When in doubt, check some references for what seems most sensible.

Well pointed out, I was going to write "basketball" (it sounded better), but I decided not doing so. I'm glad I didn't write this, for now I know why it sounds better.

About the 'work out', I was going to split it, but everyone else was using it as whole word. Does it change from case to case?

Yes, sure. I'd prefer breaking it apart as a verb, and you'd probably want to use "basketball":

• How often do you work out?
• I play basketball every Sunday.

(As a rule, we play ball. In this case, basketball. Or volleyball, baseball, etc. A departure from the Portuguese, where we say "Eu jogo baskete, volei," etc., mas, por necessidade, beisebol.)

• How often do you workouot?
• I play basket every Sunday.

Will this fit?

I'm not sure the distinction is worth the effort, Donay. We see the two terms being used pretty interchangeably.

Going for a long walk every day is enough of a workout for him.
His type of workout doesn't even raise the heart rate.
Etc.

Dicas:

Podemos utilizar "workout" como sinônimo para "physical exercise" a qualquer momento ou em apenas determinadas situações?

Não a qualquer momento.

"Workout" é um pouco mais específico e informal do que a expressão "physical exercise", que é mais formal e geral quando o assunto é "malhação/exercício físico". "Workout" é um período de "physical exercise" que você faz para se manter/entrar em forma. Há maneiras de se fazer exercício físico(physical exercise) sem estar malhando(workout) para se manter em forma.