Different body cells can respond differently to the same peptide hormones because

Activation of various components of the signal transduction pathway generates a varied response to the same hormone by different body cells.

Explanation:

Peptide hormones are water-soluble hormones and mostly have cell surface receptors present at the membranes of the target cells. Binding of these hormones to their cell surface receptors activates another messenger molecule present in the cytoplasm.

For example, activated hormone-receptor complex activates G protein to trigger the synthesis of cAMP within the cells. Activation of various protein kinases by cAMP results in phosphorylation of different proteins present in various target cells. Activation of different proteins in different target cells, as stimulated by the same peptide hormone generates varied responses.