Baritone guitars are designed for lower tunings. You can tune one to standard E tuning, but it's less common and the strings can feel overly tight.
You can tune a standard guitar down toward baritone range, but extremely low tunings can feel loose and unstable because of the standard guitar's shorter scale length.
If you regularly play in very low tunings like Drop B or Drop A, a baritone's longer scale often gives you a firmer feel and better clarity than a standard guitar.