They are both Schwinn, probably early and late production, or vice versa. I have seen the same stylized "S" of the first picture on the Schwinn branded GB stems on Sports Tourers and Super Sports.
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1971 Paramount P-13 Chrome
1973 Paramount P-15 Opaque Blue
1974 Raleigh Professional Blue Mink
1991 Waterford Paramount
Holland Titanium Dura Ace Group
Holland Titanium Ultegra Triple Group