What is the difference between ceftriaxone and cefixime?

It has a mode of action and spectrum of activity similar to those of the third-generation cephalosporin cefotaxime, but some Enterobacteriaceae are less susceptible to cefixime.

Sorry this question has not been answered earlier for you.
Both ceftriaxone and cefixime are classed as third generation cephalosporin antibiotics.
Because they belong to the same "generation" their antimicrobial properties are very similar.
Each generation has greater Gram-negative antimicrobial properties than the preceding generation, in most cases with decreased activity against Gram-positive organisms.
See the links below for more detailed information.
https://www.drugs.com/mtm/ceftriaxone-injection.html
https://www.drugs.com/mtm/cefixime.html