Pillar Candles are solid and self standing. Their shapes are typically round, but also come in square, rectangular, hexagonal, and other designs. Some may have more than one wick. Heat resistant candle bases or stands must be used.

Floating Candles have a low, stable profile and are designed to float on water. They vary in form from simple, smooth designs to elaborate, realistic shapes.

Votive Candles are normally 2 1/2" high and usually square or cylindrical in shape. They are burned safely in small, heat resistant, glass containers to control the liquefied wax as the candles burn.

Awkward because of glass containers; not a good choice.

 

Taper or Dinner Candles as they are also called, are usually 3/4" to 1" in diameter, ranging from 6" - 18" tall. Tapers need to be securely set in an appropriately designed candle holder, which will keep them in an upright position for proper and safe burning.

Container or Filled Candles are non-flammable, heat resistant containers which are filled with wax and  wick. Containers such as heat resistant glass jars and ceramic pottery are commonly used.

Tealight Candles are usually about 1 1/2" in diameter and around 3/4" high inside a cylindrical metal container. These small filled candles are used in food warmers or as candles in a tealight holder.

These are used by some pysanka makers; not my first choice.

 

Specialty Candles may be found in any three dimensional shape imaginable. They can be molded or sculpted by hand and are mostly for decorative use.

Liquid Candles are small, often disposable oil lamps.  A wick is inserted through a metal holder into a reservoir full of lamp oil. These usually burn more cleanly than ordinary candles. 

A good choice, clean burning and non-variable height.