Tamron 18 400mm f 3 5 6 3 vs tamron 18 270mm f 3 5 6 3?

Here is what the site says about that.

From Tamron 18-270mm f/3.5-6.3 Di II VC PZD: Tamron 18-270mm f/3.5-6.3 Di II VC PZD: A zoom lens by Tamron for APS-C cameras, 18-270mm f/3.5-6.3. Sold first with a gold ring (B008), later with a silver one (B008TS).

From Tamron 18-400mm f/3.5-6.3 Di II VC HLD: Tamron 18-400mm f/3.5-6.3 Di II VC HLD: A zoom lens by Tamron for APS-C cameras, 18-400mm f/3.5-6.3. An all-in-one zoom reaching 600mm equivalent (640mm on Canon).

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