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Stars are (to a first approximation) Black Bodies in the thermodynamics sense. This means that their peak radiation output depends on their surface temperature, which in turn depends on their mass. Small stars (less than 0.1 Solar masses) are red dwarfs, up to massive (10 or more Solar masses) blue-white stars.
The dark lines in the spectrum do indicate atomic composition, and these can be used to classify stars as "population I", "population II", etc., with older stars containing fewer complex elements.
Freedom is the freedom to say that two plus two make four. If that is granted, all else follows.
-- 6079 Smith W.