¿Cuál es la diferencia entre términos que coloquialmente se usan con un sentido próximo como: lengua, lenguaje, habla, discurso?

Here is my best translation:   text analysis.1. read the text.2. determine the main idea of the text.3. determine the type and style of speech.4. write out 5 words and choose synonyms for them.5. find in the text all possible language tools (trails).blessed is he who was young in his youth,blessed is the one who has matured in time,who gradually lives coldwith years i could do it; who did not indulge in strange dreams,who did not shun secular black people,who at twenty was a dandy or a grip,and at thirty is profitable married; who was freed in fifty? from private and other debts,who fame, money and rankscalmly in turn achieved,about whom they have insisted for a whole century: n. n. is a wonderful person.(as pushkin).