較差 is read as かくさ (kakusa) and means range.
かくさ
kakusa
にちかくさ
diurnal range (of temperature)
ねんかくさ
annual range (of temperature)
かくゆういろん
theory of comparative advantage
くらべもの
comparison
くらべものにならない
cannot be compared (with)
こうりょう
ちんぎんかくさ
pay gap
ないがいかかくさ
price variance between domestic and overseas markets
かかくさ
price margin
にっしんしさ
heliocentric parallax
ちしんしさ
geocentric parallax
いっぴょうのかくさ
disparity between values of votes in different constituencies