Intensional:

• Shoe: one of a pair of rigid or semi-rigid objects worn on the feet to thermally insulate them and/or to protect their skin and/or for aesthetic reasons.
• Hope: emotion usually associated with assigning a non-negligible (but usually small) probability of some desirable outcome.
• Wire: a strand of metal (or several such strands twisted together), thin enough to be flexible, often cladded with a flexible sheath of insulating material.
• Green: the colour of light with frequencies which, in vacuum, correspond to wavelengths within a couple tens of nanometres of 530 nm.
• Politician: someone holding a public office or otherwise involved in politics.
• Apple: the fruit of the apple tree (Malus domestica).

From the easiest to the hardest: apple, green, wire, shoe, hope, politician

Extensional:

• Shoe: runners, moccasins, boots, sandals, etc.
• Hope: (It is notoriously hard to define feelings extensionally. When a woman asked Napoleon how he felt when some foreign soldiers were after him, he ordered his soldiers to point their guns at the woman, and then he told her “That's the way I was feeling.” I'm gonna try to do something similar.) “Five minutes from now, I'm going to cast a die, and if the six comes up, I'm going to give you ten dollars. ... Hope is what you're feeling right now.”
• Wire: each of the strands you can find in a power cable, a network cable, a pair of earphones, etc.
• Green: the colour of chlorophyll, the second primary in sRGB, these three words (assuming you're using a colour display and no custom stylesheet or stuff like that and you've not followed the link before), etc.
• Politician: heads of state (e.g. Barack Obama), heads of government (e.g. David Cameron), ministers, members of legislative assemblies, mayors, etc.
• Apple: a fruit like the one depicted on the logo of Apple Inc., you know, the one on an iPod or a Mac.

From the easiest to the hardest: green, wire, politician, shoe, apple, hope

Apple was much easier for to define intensionally than extensionally because the membership criterion is straightforward, but I can't think of any specimen of apple the listener is likely to have seen. Politician was the other way round because there are lots of well-known people or classes of people who I'd consider to be politicians, but I can't think of a good-enough criterion.

(How damn hard is it to get the list markup to work?!?!)