The nomenclature can be confusing. Some brands call a "putty" a "fill", and vice versa.
A "
grain filler" AKA "
paste wood filler", is a product designed to fill the grain on porous open grained species, like Red Oak, and Mahogany. With woods like those you could spend your child's college education on sanding sealer and topcoat to fill the grain, unless you use a "grain filler". Worked and applied properly, it will leave a surface that takes stain well, and topcoating with a film finish will produce a finish slicker than a baby's you-know-what.
A wood filler, is a mix of fill for repairs that dries, and can be sanded. It comes in colors, and can be stained before use, or after it dries and is sanded.
Famowood wood fill is an example of that. If the project calls for stain or topcoating, a sample should be tested, as it will take on a different color, when oils or a film finish is applied.
Wood putty comes in different forms. It's available like a
crayon. Minwax also has a line of putty type pencil/crayon applicators. The putty also comes in small jars. From the jars it can be scooped out and mixed. To mix the crayon type, a rounded knife, like a flatware table knife can be used, or a spatula, to cut off small amounts and mash them up together. Most of the putties stay somewhat flexible. Ordinarily they work best on finished woodwork, applied and then rubbed off with a "T" shirt type rag.
Shellac sticks work very well for a durable fix. They come in a stick or flake form, in many colors. A hot spatula used with a small alcohol burner works the best.
Using the wood dust for the species can work to a point. Mixing with a white glue, like Elmers, makes for a fairly good match. Mixing with the finish topcoat, and adding the stain to match can help minimize a color differential. But, just like wood fill, the mixed fill will take on a different color when a topcoat is added. So, experiment with samples first.