Bromocresol green and bromothymol blue are both pH indicators

 Bromocresol green and bromothymol blue are both pH indicators, but they function in different pH ranges. Bromocresol green changes color from yellow to blue-green between pH 3.8 and 5.4, while bromothymol blue changes from yellow to blue between pH 6.0 and 7.6. 

Here's a more detailed comparison: 

Feature

Bromocresol Green

Bromothymol Blue

pH Range

3.8 - 5.4

6.0 - 7.6

Color Change

Yellow (acidic) to blue-green (alkaline)

Yellow (acidic) to blue (alkaline)

Uses

pH indicator in biology and medicine, vital stain for blood-brain permeability, tracking dye for DNA gel electrophoresis

pH indicator, photosynthesis and respiration testing