Not every published opportunity is the same kind of document. Understanding the difference between a Request for Quotation, a Request for Proposal, and a formal Invitation to Bid saves time before you invest in preparing a full submission.
Used for lower-value, more straightforward procurement, typically with fewer compliance forms and a shorter turnaround. Price and basic compliance usually dominate the evaluation.
Used when the department needs a solution, not just a product — professional services, IT systems, consulting. Expect a functionality/technical evaluation stage in addition to price and B-BBEE, often with a minimum threshold score you must clear before your price is even considered.
The most heavily regulated form, generally for higher-value, longer-term, or infrastructure contracts. Expect the full set of SBD/MBD forms, a compulsory briefing session (attendance sometimes mandatory — missing it can disqualify you outright), and a formal bid validity period you must commit to in writing.