Comparison
Recommendation vs Selection
Recommendation is being put forward as a candidate; selection is being the one chosen. Recommendation gets you onto the shortlist; selection is decided by the requirements and validation that follow. Being recommended is necessary but not sufficient for being selected.
What Recommendation is
Recommendation is the system putting your company forward as a suggested option within a set.
What Selection is
Selection is the final choice of one vendor from the shortlist, at the end of the evaluation.
Where they overlap
Both are outcomes of the same evaluation, and selection is drawn from the recommended set. Improving your recommendation position generally improves your odds of selection, all else equal.
Where they differ
Recommendation is plural and early; selection is singular and final. Between them sit the requirements and validation that can still eliminate a recommended vendor. Surviving to selection is a stricter test than being recommended.
Where both fit in the commercial evaluation lifecycle
Recommendation is the recommendation stage; selection is the selection stage near the end. Requirement evaluation and validation sit between them and decide who survives.