What this suffix does
The suffix -graphy (from Greek "graphein", to write/record) names techniques, disciplines or recording processes. From "photo" (light) you get "photography"; from "geo" (earth) you get "geography"; from "calli" (beautiful) you get "calligraphy".
-graph (without -y) names the instrument or concrete result: "photograph" is the actual photo; "photography" is the technique or art of taking photos.
The Spanish cognate: -graphy = -grafía
English and Spanish share the same Greek root:
photography = fotografía
geography = geografía
biography = biografía
calligraphy = caligrafía
Only the ending changes: -grafía → -graphy. If you know the Spanish term, you already know the English.
The -graphy / -graph / -grapher / -graphic family
From "photography" come four related words:
photography = the technique
photograph = the photo (or shortened to: photo)
photographer = the professional
photographic = the adjective
The same structure applies to geography (geographer, geographical), biography (biographer, biographical), etc.