Suits

Power Suit: The power suit is the first suit Samus starts out with (other than the Varia Suit which you lose at the very beginning before escaping the Space Pirates ship). The Power Suit gives her a decent amount of protection but not a lot.

Varia Suit: The Varia Suit is the upgraded version of the Power Suit. It gives Samus more protection and lets her withstand high temperatures.

Gravity Suit: The Gravity Suit lets Samus run and jump normally. It also gives Samus a little bit more protection also.

Phazon Suit: The Phazon Suit is the final suit Samus gets. This suit gives her maximum protection and allows her to move in deadly phazon without being hurt, hence the name Phazon Suit. When fighting final boss, the Phazon Suit allows you to use the Phazon Beam. (See beams section for more information)

Visors

Combat Visor: This is the default visor which you mainly play with. Water and mist will sometimes splash onto your visor temporarily mess up your vision. Also bright flashes will let you see some of Samus face.

Scan Visor: The Scan Visor is used to scan creatures and hidden symbols on computer equipment

Thermal Visor: The Thermal Visor lets you see in dark rooms and heated objects that need to be activated. Also it lets you see cloaked enemies.

X-ray Visor: the X-ray visor is used to see invisible objects like enemies and platforms. Also it will let you see throw breakable walls that have upgrades behind them.