Scheme as defined in R5RS is not case sensitive when reading symbols. Guile, on the contrary is case sensitive by default, so the identifiers
guile-whuzzy
Guile-Whuzzy
are the same in R5RS Scheme, but are different in Guile.
It is possible to turn off case sensitivity in Guile by setting the
reader option case-insensitive. For more information on reader
options, See Scheme Read.
(read-enable 'case-insensitive)
Note that this is seldom a problem, because Scheme programmers tend not to use uppercase letters in their identifiers anyway.