A simple way to answer this question is: denote by $Spec$ the homotopy category of spectra, $Spec _0$ the category of (-1)-connected spectra, $InfL$ be the homotopy category of infinite loop spaces. The assertion that "connective spectra are the same as infinite loop space" simply means that the composition of functors $$Spec \to Spec _0 \stackrel{\Omega ^{\infty}}{\to} InfL$$ is an equivalence.
user43326
- 3.1k
- 17
- 25