I have two regions like this
reg1 = ImplicitRegion[(-5. + x)^2 + (-3. + y)^2 <= 0.25 || (0.386909 + x Tan[25 \[Degree]] <= y <= 5.61309 - x Tan[25 \[Degree]] && 0 <= x <= 5.), {x, y}]; reg2 = ImplicitRegion[(-5. + x)^2 + (-3. + y)^2 <= 0.49 || (0.166233 + x Tan[25 \[Degree]] <= y <= 5.83377 - x Tan[25 \[Degree]] && 0 <= x <= 5.), {x, y}]; Show[RegionPlot[reg1, AspectRatio -> Automatic], RegionPlot[reg2, AspectRatio -> Automatic]] I need to see and work with their difference
RegionPlot[RegionDifference[reg2,reg1], AspectRatio -> Automatic] but it brings about an error
RegionPlot::invplotreg: {RegionDifference[ImplicitRegion[Plus[<<2>>]^2+Plus[<<2>>]^2<=0.49||(0.166233 +Times[<<2>>]<=y<=5.83377 +Times[<<3>>]&&0<=x<=5.),{x,y}],ImplicitRegion[Plus[<<2>>]^2+Plus[<<2>>]^2<=0.25||(0.386909 +Times[<<2>>]<=y<=5.61309 +Times[<<3>>]&&0<=x<=5.),{x,y}]]} is not a valid region to plot. >> 

w3andw2? Maybe you meantreg2andreg1; in that caseRegionPlot[RegionDifference[reg2, reg1], AspectRatio -> Automatic]works with no problems. $\endgroup$