1) We generally use "idioma" to say "language", we use "lengua" to mean "tongue". In this precise sense we say "Yo hablo varios idiomas" (I talk several languages), or we can also say "Esta es mi lengua nativa" (This is my mother tongue). 2) Once this has been clarified, we use "segunda lengua" (second language), "lengua franca" (lingua franca), "lengua extranjera" (foreign language)... etc. But we say "El idioma inglés" (the English language) 3) As I see it we also use "lengua"(langue) as opposed to "habla"(parole). In this sense we use "langue" to mean the abstract linguistic system, and we use "parole" to refer to the actual linguistic performance of the individuals. 4) We also have another word "lenguaje" , with the same root as English "language", but to mean the system or the ability, sometimes it can even used as a synonym of the previous ones. Therefore: "lenguaje corporal" (body language), "lenguaje de signos" (sign language)... To summarize: there are some cases when some cases aren't clear at all, and they can act as synonyms, when you talk about a language you generally would prefer to use "idioma" and when you have other usages you'll likely will use "lengua". Try to avoid "Me gusta aprender lenguas" (I like to learn tongues), you should use "Me gusta aprender idiomas" (I like to learn languages) since the word tongue can sometimes mean that thing, but in this position sounds as if we were talking about the body part.

Hola! De acuerdo al contexto de lo que quieres decir, si te refieres a la lengua como un órgano que es parte del cuerdo humano, no es lo mismo, no significa lo mismo. Pero, si el contexto de lo que hablas es referente al idioma, puedes utilizar "lengua" como sinónimo de idioma, es decir, en este caso significa lo mismo. Espero haberte ayudado :)

Hi Katie! Yes!! they have the same meaning but "Idioma" could be more used in some other countries and sometimes could be a bit more professional than "lengua" or "lenguaje" ( no much difference though).

hi