I must assume that there are two fields involved, Score, and Level. Substitute the precise field name references for these names in your expressions.
You can create one conditional format expression for each color. The order of expressions from top to bottom is important for this to work. FileMaker evaluates these from top to bottom and applies each color in that sequence so a difference between score and level of -1.6 will first produce an Orange color but then that will be replaced by Red when the last expression is evaluated.
( Score - Level ) = 0 (Yellow)
(Score - Level ) > 0 (green)
(Score - Level ) < 0 (Orange)
(Score - Level ) > 1.5 (Dark Green)
(Score - Level ) < -1.5 ( Red )