There is a complex map showing the temperture zones for plants, and books about conifers often show these. The areas take into account the topography of the land mass, which includes altitude. Many conifers are very hardy, but the fact that they are almost universal in one form or another across the zones means that they are very popular everywhere. Add to this the drama of new genera, like the Metasequoia glyptostroboides (Dawn Redwood) which was first made known in the West from discoveries in China in the 1940's, and the Wollemia Nobilis as recently as 1997, and interest is maintained. The story of the Wollemia nobilis is particularly interesting, and a dedicated web site is available. Most conifers are evergreen, but the Metasequoia and the Larix are deciduous. Some aouthors describe Ginkgo biloba as a conifer (also deciduous), it seems to be quite different from what we commonly call conifers.
The hardiness zones are well described in 'Manual of Cultivated Conifers' by Gerd Krussman. There are 10 zones, 1 being arctic and 10 being tropical. At best they are only a rough guide, as rainfall, soil and location (sun/shade/wind) all influence hardiness. Most useful is the ability of plants to survive at the low termperature end. Most of the UK lies in the zone 8 band (-12 to -7 deg C), but the Western extremes are zone 9, with central Eastern Scotland in zone 7. If you look at Canada at the same latitudes as Britain (50 to 60 deg North), you find zones 2-3! It all goes to show how benign Britain is, due to the gulf stream, even if you might not think so; and of course, if you accept that global warming is happening, it is all in a state of flux anyway.