The following two plots are not visible when shown togather:

` tr1 = With[{a = 0.1}, Composition[TranslationTransform[{0, 0, a}], ScalingTransform[{Sqrt[1 - (2 a - a^2)], Sqrt[1 - (2 a - a^2)], (1 - (2 a - a^2))}]]]; plot1 = Region[TransformedRegion[Sphere[], tr1], PlotTheme -> "Detailed", PlotRange -> {{-1, 1}, {-1, 1}, {-1, 1}}, AxesOrigin -> {0, 0, 0}, AxesStyle -> Directive[Black, 17], AxesLabel -> {x, y, z}, AxesEdge -> Automatic] tr2 = With[{a = 0.2}, Composition[TranslationTransform[{0, 0, a}], ScalingTransform[{Sqrt[1 - (2 a - a^2)], Sqrt[1 - (2 a - a^2)], (1 - (2 a - a^2))}]]]; plot2 = Region[TransformedRegion[Sphere[], tr2], PlotTheme -> "Detailed", PlotRange -> {{-1, 1}, {-1, 1}, {-1, 1}}, AxesOrigin -> {0, 0, 0}, AxesStyle -> Directive[Black, 17], AxesLabel -> {x, y, z}, AxesEdge -> Automatic] Show[plot2, plot1] `

How can one plot these with different colors and adjust the transparency such that they are visible neatly?