When two bids for the same project come in thousands of dollars apart, the difference is almost never that one contractor is cheaper. It's that one bid includes things the other one doesn't, and you'll find out which when the change orders start.
A complete foundation and framing bid should break out, at minimum: site prep and grading, foundation forming and concrete, rebar and hold-down hardware, lumber and engineered wood, labor, and the sequence of inspections. If the bid is a single number with the word 'framing' next to it, ask for the breakdown.
Check that the bid references the actual structural drawings. Shear wall schedules, header sizes, and hold-down locations come from the engineer, not the framer, and a bid that doesn't mention them may be priced on a guess.
Look for the license number. In California, any job over $500 in labor and materials requires a licensed contractor, and the CSLB website lets you verify a license, its classification, and its bond and insurance status in about a minute. Ours is #1097742.
Finally, look for a schedule. A real bid has a start date, a target for the framing inspection, and a finish date. It's the single best indicator that the contractor has actually thought through your project rather than just pricing it.
If you have a bid in hand and want a second opinion, send it over. We'll walk through it with you, no obligation, and give you a written estimate of our own to compare it against.