The difference between Fantastic and Fantastical

When used as adjectives, fantastic means existing in or constructed from fantasy, whereas fantastical means of or pertaining to fantasy.

Fantastic is also noun with the meaning: a fanciful or whimsical person.

check bellow for the other definitions of Fantastic and Fantastical

Fantastic as an adjective:

Existing in or constructed from fantasy; of or relating to fantasy; fanciful.

Examples:

"He told fantastic stories of dragons and goblins."

"His fantastic post-college plans had all collapsed within a year of graduation."

"She had a fantastic view of her own importance that none of her colleagues shared."
Fantastic as an adjective:

Not believable; implausible; seemingly only possible in fantasy.

Examples:

"The events were so fantastic that only the tabloids were willing to print them."

"She entered the lab and stood gaping for a good ten minutes at the fantastic machinery at work all around her."
Fantastic as an adjective:

Resembling fantasies in irregularity, caprice, or eccentricity; irregular; grotesque.
Fantastic as an adjective:

Wonderful; marvelous; excellent; extraordinarily good or great (used especially as an intensifier).

Examples:

"I had a simply fantastic vacation, and I can't wait to tell you all about it!"