Welcome to this forum.
There are several types of swf tanks that you can have. Generally they break down to
'fish only' or 'reef'. The difference here is that the reef will contain 'inverts'..these inverts
can be snails, corals, anenome....and may or may not contain fish.
It is generally more time consuming to keep a reef tank than a fish only tank because the
'inverts' are more sensitive to water quality issues..temperature, salinity, nitrogens (ammonia/nititres'nitrates) than would be 'fish only'. In addition, depending on what you keep in the 'reef' you have to be concerned about lighting ALOT more than in a fish only tank.