The project manager is more paid than the solution architect. In such a corporate environment (which is a very complex hierarchy), the project manager reports to the PMO, and the solution architect reports to his line manager (the solution architect does NOT report to the project manager). The solution architect designs the system to be installed at the client's premises, the solution integrator implements and integrates the system at the client's premises. The solution integrator reports technically to the solution architect, and also reports to the project manager when it comes to the project, and, of course, to his line manager.
The project manager manages the integration of the project on site.
In case of a problem during the integration (that may be resulting from an unstable system), the solution architect is called in to fix the problem on site.
How do I know all these things? I have worked with Ericsson people before and I know their hierarchy by heart.