You will find that all soft woods are conifers, but there are ecceptions to the rule. A Tuplip or Poplar as they are sometimes known is one of the only hard wood conifers, they can be found all over the uk and quite easy to identify. most conifers have branches that flow down from the trunk a tulip's go up and level out. Also if you take pine for example, if the tree grows in a valley the ones at the bottom will grow quicker, have more knots and split easier. These are known as white wood, the sort of stuff you find in B&Q which you can never find a straight piece. The trees at the top of the valley grow slower due to less moisture than at the bottom. These are better quality stronger and will provide a hard wood to work with. These woods are more expensive to buy and are only used for high quality furnitre. There are variations in all timber depending on were it grows, climate and polution levels.
As a rule if you are making something that you want want to last collect wood from high ground, or go to a timber merchant, it will be more expensive but the end result will be worth it.
Hope this helps.
Stan