Ghastly, grisly, gruesome, macabre, grim, lurid are comparable when they mean horrifying and repellent in appearance or aspect.
Ghastly suggests the terrifying aspects of death or bloodshed. The term also is used as a strong intensive equivalent to hideous or horrifying.
Grisly and gruesome imply an appearance that inspires shuddering or uncanny horror.
Macabre may imply marked or excessive preoccupation with the horrors especially of death or it may come close to ghastly in its implication of a hideous or horrifying quality.
Grim suggests a fierce and forbidding aspect.
Lurid comes into comparison with ghastly as referring to light or color; it suggests either a ghastly pallor or coloring reminiscent of death or more frequently a sinister and murky glow. Sometimes lurid differs little from gruesome except, possibly, in its stronger suggestion of sensationalism.