Types of peaches

http://www.michiganpeach.org/facts/types.html
Melting flesh peaches (left top). Melting flesh peaches have flesh that become soft over time when canned. They tend to have ragged edges when sliced during processing. Melting flesh types can be clingstone or freestone. (The pits of freestone peaches are easy to separate from the flesh).

Non-melting peaches (top right). Non-melting peaches remain firm after canning. They are selected to have orange flesh color with no red, and a distinctive taste a little like apricots. Most commercial canned peaches are non-melting types. Non-melting types are less subject to bruising during harvest than other peaches. All non-melting types are clingstone, meaning the flesh adheres to the pit when ripe. There are many intermediate types between melting and non-melting types. Peach breeders have been utilizing a genetic characteristic called stony hard. Fruit with a stony hard gene are very slow to soften.

http://www.ent.uga.edu/peach/peachhbk/preplant/varieties.pdf
Most commercial peaches grown in the eastern states are yellow-fleshed freestones, except for the early season varieties, which are mostly clingstones. Freestone peaches have melting flesh that becomes soft and juicy as it ripens. Retail and wholesale markets have grown accustomed to yellow, melting-fleshed peaches. Some of the peaches grown in California are used for canning; these have a more resilient flesh texture, known as non-melting because they stay firm as they ripen. Non-melting peaches are suited to canning because the flesh stays intact during processing. Some of the newer fresh market varieties such as Springprince, Gulfprince, and Crimson Lady also have non-melting flesh. All non-melting peaches so far are clingstone, which is not a problem for early season fruit because all are more or less clingstone. Although there are a few mid to late season clingstone peach varieties available for fresh market use, it is not clear how well they are accepted by buyers and consumers accustomed to freestones at that time of the season. However, many popular late season nectarines are clingstones. Non-melting flesh improves the firmness and eating quality in the early season if the fruit is left on the tree longer. However, non-melting varieties may develop off-flavors if allowed to over-ripen on the tree.

In recent years, growers in California have planted white-fleshed peaches, initially for the Pacific Rim export market. More white-fleshed peaches are showing up in domestic markets. The new white varieties are mostly low-acid types, in contrast to most yellow peaches and the white varieties of years past such as Georgia Belle. Generally, the newer varieties are much firmer and with redder skin than the old ones. The low-acid flavor may seem bland to people used to standard peaches, but are often preferred in Asian and some Hispanic communities. One advantage of low-acid fruit is that there is little unripe (green) flavor so fruit can be eaten crisp, and time of picking is less critical to the ultimate flavor. The newest wave of peach varieties from California are low-acid yellow-fleshed peaches.

Yellow and white fleshed peaches. Most peaches grown in the United States have yellow flesh. In some areas of the world such as Asia, white flesh peaches are preferred (lower right). The white-fleshed peaches have very light or white flesh. They are often red or pink near the pit