What are the requirements for the different endings in Metroid?

What are the requirements for each different ending in Metroid and what are the differences between each of them?

Solution 1:

There are 5 different endings. You can see screenshots of all of them along with requirements here: http://www.vgmuseum.com/end/nes/b/met.htm

• Under 1 hour: Samus removes her suit, revealing a bikini
• 1-3 hours: Samus removes her suit, revealing a one-piece swimsuit
• 3-5 hours: Samus removes only her helmet
• 5-10 hours: Samus waves, but leaves her suit on
• 10+ hours: Samus turns her head away in shame

The Metroid Database lists slightly different requirements for the two worst endings:

• 5+ hours, played with normal Samus: Samus Waves, but leaves her suit on
• 5+ hours, played with suitless-Samus: Samus turns her head away in shame

I'm not sure which is correct.