what is "field_create_field" and "hook_field_info"? is there difference motive I want to create a field, i searched on drupal and find field_create_field can create a field but I also find that hook_field_info is also to create to field.

My question is what is basic difference between both of them?
Are they use for same purpose?

I need the difference and where both are used?
function field_create_field is used to create a field. When you debug this function you will get $field array with the id property filled in.

function hook_field_info defines Field API field types. For more info refer here. 

For more clarification you can simply debug both these functions then you will get the all basic differences.