Hi David,
Yes, it does make a difference.
Hybrids(F1) are varieties that won't come true from seed. Which means the plants from seeds you saved will vary. How much they vary depends on the genetic makeup of the hybrid.
Open Pollinated(OP) varieties will come true from seed. Though some types of plants readily cross with other plants growing in your garden or your neighbors' gardens. So you do need to know which types are more promiscuous.
Heirloom is a term for an old variety,but some OP varieties are new.
Some perennials will come true and some are VERY promiscuous. Columbines cross readily in the garden. Coneflowers will cross so if you lets say have 'White Swan' in your garden, but your neighbor has a pink cultivar. Your seed saved of 'White Swan' will produce seedlings in various shades of pink.
Dianthus I've found to be more true to the parent.
On the Winter Sowing forum, they have been working on a chart of plants and their offspring whether they come true or not. You might like to check that out.
Remy

can you tell me how to find that chart on the winter sowing forum? Thanks!