Question

-ir and -er ending verbs are very similar in their endings when they are conjugated. How do they differ in their endings when they are conjugated?

Answer 1

Which language do you mean — Spanish, French, or another language?

If you mean Spanish (the most common case): regular -er and -ir verbs use the same endings in most tenses (preterite, imperfect, future, conditional, present subjunctive, past participle, gerund, etc.). The main differences are in the present indicative and the present indicative-derived vosotros forms:

- Present indicative:
- -er: yo -o, tú -es, él/ella -e, nosotros -emos, vosotros -éis, ellos -en
- -ir: yo -o, tú -es, él/ella -e, nosotros -imos, vosotros -ís, ellos -en
So the differing endings are nosotros (-emos vs -imos) and vosotros (-éis vs -ís).

Also note: some irregular stem changes behave differently in -ir verbs (e.g., certain stem vowels change in the nosotros/vosotros or in the preterite third-person), but that's about irregulars, not the regular endings.

If you meant French, the difference is larger: regular -er verbs (parler) use -e, -es, -e, -ons, -ez, -ent while many regular -ir verbs of the “finir” type use -is, -is, -it, -issons, -issez, -issent (notice the -iss- in nous/vous forms). Say which language you want more detail for and I’ll give full tables and examples.