'Improve' and 'enhance' are very close - they mean that something is better. However, enhanced can refer to improved clarity in a picture, whereas if you used improved, you would have to add the word 'clarity'. 'Increase' just means that something grows in size or number. It does not necessarily mean better. If pollution increased or the number of robberies in an area increased, that would obviously not be good. 'Develop' is also neutral. Most of the time it means to increase in size or quality, but it can also mean something negative. "He developed into a bully" would not mean something positive. "He developed his math skills" would be a positive statement.

it is hard to explain because they all mean rothly the same thing but I hope I can help a bit. improve-getting better at something for example.you'r drawing skills are improveing meaning you are getting better at drawing. enhance-is the same as improve you are getting better at something increase-can mean you are getting a bigger amount of something for example.this year you'r profit has increased by 25% meaning you have more of something develop-can mean you have becore more mature or mean you have become more advance at something so improveing I hope this helped a bit and is not to complicated