First, let’s deal with the pronunciation of `obsolete’. The first syllable rhymes with `sob’, `cob’ and `mob’. The second `o’ is like the `a’ in `china’, and the final `lete’ rhymes with `neat’, `beat’, and `meat’. The main stress is on the final syllable `lete’. When you say that something is `obsolete’, what you mean is that it has gone out of fashion; it is outdated. It is no longer required or no longer in use because something new and better has taken its place. For example, computers have made typewriters obsolete; the `tonga’, which was quite popular once upon a time, has become obsolete.
Example: We don’t have spare parts for your computer. The model has become obsolete.
`Junk’, unlike the word `obsolete’, is mostly used in informal contexts. When you say that something is `junk’, what you mean is that it is worthless. The object is fit to be thrown away. Something that is new, but is of no value, can also be called `junk’. `Obsolete’, on the other hand, does not carry this meaning. The word merely suggests that the equipment has become outdated — it could be an outdated piece of equipment that still works. A piece of junk, on the other hand, could be an outdated piece of equipment which may or may not work. Either way, you want to throw it away. Not everyone throws away an obsolete piece of equipment.
Example: You’ve had that scooter for over 20 years now. Get rid of the junk.