Bonus amounts depend on the company policy. For example at Google the bonus is supposed to be counted as part of your total comp and is always targeted to be 15% of your base salary but can be higher if you perform better than expected for your role. Example: if your base is 100k at Google, you can expect (unless you somehow screwed up that year) at LEAST 15k come bonus time once a year. You could also have a 1 time starting bonus. At places like Amazon there isn't (afaik) a general bonus policy and any bonus comp mentioned is usually part of a starting bonus only.
Part of total comp and % of base that recruiter tell you about. Although, some people actually don’t realize this and hence put sign on amount there instead. So take the data with grain of salt
Levels form explicitly asks for annual bonus and sign on bonus. The number that levels reports is 100% annual + 25% sign-on