Price to earnings uses the last reported annual earnings. In an IPO these earnings can be affected by one-time items, so read the notes.
Price to book compares the price with net worth per share. It is more useful for asset-heavy businesses such as real estate or lending.
Where peer data is missing or the peers are not comparable, the honest conclusion is that valuation cannot be assessed confidently.
An easy example
A P/E of 34 means the price equals about 34 times the annual earnings per share. A comparable listed peer at 29 is priced lower relative to earnings.
Important note
Ratios only make sense against genuinely comparable companies in the same industry and of similar size.
Common mistake
Comparing a small company against a much larger one and concluding the smaller one is cheap.