I will touch on something that everyone else seems to be taking for granted - salary is a complicated concept. There are a few factors that you need to consider when comparing salaries from two different companies.

The first thing I will look into is 401k. Early stage startups do a particularly bad job of this. Ask if you have an employer-sponsored 401k plan and how much the employer will contribute. I'd also ask about the investment options, just to be safe.

Next is healthcare package. Ask for the full prospectus for all available options and how much they cost, after employer contribution. Also make sure that your dependents are covered too.

Ask about WFH policy. If you don't have to commute to work everyday for 9 AM meetings, you can save a lot and live better by living further away from city center / downtown area.

Make sure you have enough PTO for vacations. Ask about accrual policy and make sure their policy is to pay you for unused PTO when you leave.

If you have a bonus target, make sure you know exactly what you have to do to get all / most of it. It is easy to promise bonus when they can get away without paying it.

There are many more points like the above. The cost / savings from these add up. You are the only one who can do the math and decide whether it is substantial or not.