In brief
The similar shape with a carrot does not mean that we should use it without regard to texture.
Useful to know
When choosing parsnips look for hard roots; smaller ones are usually gentler. Iowa State describes its use in soups and other cooked dishes, including as an alternative in some carrot recipes. It is a possibility of use, not a statement of the same taste. [1]
For a tray of different vegetables, cut the pieces according to the desired result and follow the specific recipe. The same length of raw roots does not automatically mean the same processing time.
When you first replace an ingredient, choose a simple preparation and a small amount. This will help you decide if the flavor and texture suits you before you change the whole dish. When buying, look at the hardness and condition of the surface, instead of choosing only the largest root.
Sources
For further detail and to check the information: