The difference between original car paint and rear paint:

The car paint sprayed on the car production line is divided into four layers: electrophoretic layer, middle coat layer, colored paint layer, and varnish layer. (Pearl Paint seems to need another procedure)
The electrophoretic layer is the “primer”, and the first process is to prevent corrosion.
The middle coating is applied on the electrophoretic layer. The entire body is completely immersed in a large pool filled with paint and then electrified. This process is called electrophoresis. The middle coating plays a role in protecting the electrophoretic layer and improves corrosion resistance.
The color paint layer is the color of the car body we see.
The varnish layer is a protective paint, which improves hardness, prevents small scratches and scratches, and has a certain anti-corrosion effect.
The paint sprayed after the 4S shop or repair shop has no electrophoretic layer on the post-repair paint. Some repair shops cannot even spray primer. It is precisely because of this that problems such as poor adhesion can be caused. Over time, the color difference is obvious.
In addition, after the automobile production line paints the car body, the car body frame has to be baked at a high temperature of 200 degrees Celsius. At this time, nothing is installed on the car body frame. If the paint is repaired after leaving the factory, the interior and some parts cannot withstand the high temperatures. Also, the dust-free level on the automobile production line is much higher than that of 4S shops or repair shops.

Therefore: the after-touch paint is definitely not as good as the original car paint.

Small scratches, no exposed bottom, no color difference, you can try to handle them by polishing.
The front and rear bumpers are made of plastic, and no matter how deep the scratches are, there will be no corrosion. Whether you make up for it depends on the individual. You can buy some lacquer pens to repair it.
If the primer is exposed in other places, it must be dealt with in time. Once the time is long, once the rust wears out, the maintenance cost will be high.

The following are the steps I used to repair the scratch on the door using the paint dot method. Several places have already been left out. You can refer to it. If a motorist has a better repair method, you can also reply.
1: Clean the car door, use 1500 sandpaper dipped in water to remove and smooth the deep scratches to increase the adhesion of the paint.
2: Paint, remember to paint it thicker. After waiting for a day, it was almost cured.
3: Use 2000 sandpaper to soak it in water and smooth it down. There will be no bumps and bumps when touched by your hand.
4: Polishing locally with abrasive wax.

This method does not damage the original paint. It cannot be seen without careful inspection after repair. Of course, it does not have the effect of spraying the entire topcoat. You can decide which is better or worse.