matching colors in adjoining Layers

If the problem is that one of the greens is lighter, then one approach is to take advantage of the fact that Curves lets you place multiple points across the tonal range. Maybe at least one channel’s curve needs a minimum of two points added to it: One point in the lighter tones to correct the lighter green, and another point in the darker tones to correct the darker green.

This is much easier and faster if you’re taking advantage of:

• Eyedropper tool color samplers.
• Info panel readouts for each sampler, so you can compare before/after numbers of the multiple colors that must match on each side. 
• The Target Adjustment Tool, so that you can drag directly on the image to affect the tones that need correction. It will automatically add and shift curve points where you drag it on the image. 

That way, you can look at the numbers reported by the color samplers as you adjust each tonal range, and make sure they are the same for the critical colors on both layers, as shown in the demo below.

Basically what I do in the demo is:

1. (not shown) Use the Eyedropper tool to add four color samplers, one pair for the each pair of greens that need to match across the layers. This is done by Shift-clicking the Eyedropper tool on the canvas. Then I open the Info panel so I can monitor the samplers’ color values. 

2. In the Properties panel for the currently selected Curves layer, I switch to a color channel, starting with the first one, Red.

3. Match color sampler RGB values in sampler #2 to the readout in sampler #1, by dragging the Target Adjustment Tool over the lighter green that needs to match the red channel value in the other layer until the sampler #2 value matches sampler #1. That takes care of the lighter green. 

4. Repeat step 2 by dragging the tool over the darker green near sampler #4, to match its red channel value to sampler #3. 

5. Repeat steps 2 and 3 for the other color channels. This is an RGB image, so I went on to correct the lighter and darker green for the green and blue channels too. 

6. After the RGB values on both sides match up for corresponding color samplers, their colors should visually match up too. 

7. I switch back to the composite curve view, where the adjusted curves can now be seen for all channels.

The greens in the demo might look like they don’t exactly match at the end. They do in the original screen recording, but what’s shown here is subject to the color quality limitations of the animated GIF format.

I am not sure I understand your request. Let me try. If you want to match less saturated green with more saturated green, then use a Hue/Saturation adjustment layer clipped to the less saturated layer and drag the Saturation slider. If that doesn't work, try adjusting all three available sliders; most likely, Saturation and Lightness will do the trick.