A painting typically uses a brush, paint, and water. The style and size of the brush vary. The paint can come with ROYGBIV (the rainbow) and white, black, brown. You can create more colors by blending them and you can also make a shade lighter by adding white and darker by adding black. Water is use for the purpose of cleaning the brush, unless you are water-color painting. A painting can be themed by a historical event, still life, portrait, or it can be abstract.
Sculptures are more difficult because it often requires tools. When sculpting you can you use stone, wood, clay, metal and even ice. It requires skill except when you are using clay. Metal sculptures require welding. Wood needs a strong cutting tool, not necessarily a chainsaw. Clay is fun because you can use your hands and a child could literally do it. Stone and ice require a hammer and chisel.
A collage is simplely a multitude of pictures put together with a purpose. Some collages are in a shape and some have a shape within them. A collage does not require a shape as long as the pictures relate in one way.