inflexible vs sturdy

inflexible and sturdy both are adjectives.

Word	Noun	Adjective	Verb	Adverb
inflexible	No	Yes	No	No
sturdy	No	Yes	No	No

As adjectives, inflexible and sturdy are synonyms defined as:

Other synonyms of inflexible include uncompromising.

inflexible (adjective)	sturdy (adjective)
resistant to being bent	not making concessions
incapable of change	having rugged physical strength; inured to fatigue or hardships
not making concessions	substantially made or constructed
incapable of adapting or changing to meet circumstances