The difference between CGI.escape and URI.escape

cgivsuri.rb

require 'uri'
require 'cgi'

puts ["i", "i.chr", "URI.escape", "CGI.escape"].collect { |x| x.inspect }.join("\t")
(0..255).each do |i|
  chr = i.chr
  cgi = CGI.escape(chr)
  uri = URI.escape(chr)
  puts [i, chr, uri, cgi].collect { |x| x.inspect }.join("\t") if cgi != uri
end

Output

"i"	"i.chr"	"URI.escape"	"CGI.escape"
32	" "	"%20"	"+"
33	"!"	"!"	"%21"
36	"$"	"$"	"%24"
38	"&"	"&"	"%26"
39	"'"	"'"	"%27"
40	"("	"("	"%28"
41	")"	")"	"%29"
42	"*"	"*"	"%2A"
43	"+"	"+"	"%2B"
44	","	","	"%2C"
47	"/"	"/"	"%2F"
58	":"	":"	"%3A"
59	";"	";"	"%3B"
61	"="	"="	"%3D"
63	"?"	"?"	"%3F"
64	"@"	"@"	"%40"
91	"["	"["	"%5B"
93	"]"	"]"	"%5D"
126	"~"	"~"	"%7E"