First, there is no difference in pronunciation of the two instances of spring in the last sentence of your example. True, it is the exception to the pattern in the preceding lines. And the meaning is different in each usage of spring.
Two words with the same spelling and same pronunciation, with different meanings, such as spring in your example, are Homonyms, see chart below.
All the other examples had the same spelling, different pronunciation and different meanings. They are Heteronyms.
This is probably a bit of overkill, but I like this kind of thing, and was excited to find this cool Venn diagram just now, so posted what is mostly a repeat of fortunate1's fine answer.
See Venn diagram from Wikipedia of terms for words with similar pronunciation, meaning and spelling, or any combination http://i.stack.imgur.com/sMlIE.png
I couldn't insert the image because I am new on the English Stackexchange site, sorry!