Speech and Language seem to be used synonymously. However, they are different things entirely. Let's break it down for you just a bit.
Speech is the actual production of sounds that build to make words. Speech has to do with your articulation, fluency, nasality, and voice. 1. Articulation: This refers to the actual production of the sounds. Does your child say "wabbit" instead of "rabbit"? We would say that he/she has an articulation disorder. 2. Fluency: This is a fancy word for stuttering. If your child stutters (and therefore does not have fluent speech), then we would say that your child exhibits dysfluency. Please see my blog post from January 3, 2012 for more information about stuttering in small children. 3. Nasality: Some of our sounds come out of our nose (m, n, and ng), but most should come out of our mouth (oral cavity). If you can think about someone who has a a cold, their sounds are typically de-nasaled. Their /m/ may sound more like a /d/. Whereas, some people have a more nasal-sound to them and more than just the 3 nasal sounds are actually being phonated through their nose (naval cavity). 4. Voice: Your voice can refer to the volume that is used and the quality of your voice. If you "lost your voice", then we would say that you had a breathy sounding voice. Sometimes people who are just getting their voice back after "losing it" will have a harsh sounding voice. All of these components make up your speech. All of the areas mentioned above are within a speech-language pathologist's scope of practice and can be worked on to correct if there is something wrong.
If speech is how you are saying things (the mechanics) then language is what you are saying. Language is what you understand, how you use words to communicate, and how you string those words together to create phrases, sentences, and paragraphs. There are two types of language: receptive and expressive. Receptive language is sometimes called "Auditory Comprehension." That's actually a really great descriptor of receptive language. Your auditory comprehension (receptive language) is what you hear, understand, and respond to. You would see it come in the form of kids following directions, pointing to things requested, retrieving objects, etc. Your expressive language is what you are actually telling us - how you are communicating.
I hope that clears things up a bit!