Title says all about the question. I have three guitars, electric and two other which i don't know if it's classical or acoustic. They both have same shape, guitars don't have cut at higher frets like electric does and also they have wide fretboards.
Classical guitars are designed to be played primarily finger-style (fingerpicking). They generally use nylon strings which do not require near the same amount of tension as steel strings. Because of the lower tension, they do not require a truss rod to compensate for the string tension.
Steel string or folk guitars use steel strings and will have an adjustable truss rod with an adjustment screw visible from the soundhole - or under a plate in the headstock.
The neck on many classical guitars will join the body at the 12th fret whereas "steel-string" or "folk" guitars, will usually join the body at the 14th fret.
The bridge on a classical guitar will usually not have bridge pins or holes through the bridge into the body of the guitar, but will allow for the string to pass through the bridge itself (not the top of the guitar) and be tied on to the bridge with a special knot.
Guitars designed for steel strings will usually have holes through the bridge and top of the guitar where the ball at the end of the steel string will pass through and be secured against the top with removable bridge pins. This is because the tension of steel strings could otherwise have a tendency to pull the bridge away from the top of the guitar. Some manufacturers make bridges for steel string guitars where the string passes through a thin diameter hole that is too small to allow the ball end to pass through. But I'm guessing they might use more than just glue to fasten the bridge to the top of the guitar.
Usually the tuning pegs on a classical guitar are not actually pegs, but more like bars that the string winds onto over the top.
Tuning pegs for steel string guitars usually are perpendicular to the headstock and the string winds around them either counter clockwise or clockwise depending on which side of the headstock they are on.
The neck on a classical guitar is much wider than on a steel string guitar to allow for wider string spacing.
These clues should allow you to determine if your acoustic guitar is a classical guitar designed for nylon strings - or a steel string guitar designed for - well - steel strings.
All classical guitars are acoustic. The differences come in when you consider the string material (classical acoustics usually have plastic strings in my experience) and a wider and bigger fretboard.