Only the RV200 core (Radeon 7500) and R200 core (Radeon 8500) are made with the .15 micron process; the R100 core (which is used by the Radeon 7200, LE, 64mbDDR, 32mbDDR, 32mbSDR, among others) and the RV100 core (Radeon VE and 7000) are made with the .18 micron process.
As for which is better between the LE and the 7200, they're roughly the same, with the LE probably holding a slight edge. But to some, the 7200 makes up for it because its' warranty is honoured by ATi, not Althon Micro (the Radeon LE is technically a 3rd party graphics card, even though at the time ATi wasn't officially selling the Radeon core to other manufacturers). It is also said that the LEs are the last "test" batch of Radeon cores, including the "A12" core denotation (which I can verify that my LE has the A12 marking on the core), instead of the "A13" denotation of all the retail ATi cored boards. The initial Radeon 8500 preview by Tom's Hardware mentioned that their test board had an "A12" core, while the retail boards were to have "A13" cores (which means a later version with slight revisions). It makes me guess that a similar situation was done with the R100 core - the last "test" revision was sold as a budget part to help keep costs down, instead of scrapping a perfectly good batch (albeit maybe a little rough around the edges) of cores. I wouldn't be suprised to see some of the budget 250/250 and 230/230 clocked Radeon 8500s using an A12 revision core.
As for clock speed, in another forum one 7200 owner posted his speed as 155/155, and with the fact that the 7200 only comes with a heatsink and is priced for the budget market, I think that's about right. The LE is clocked to 148/148 stock, but many owners have gotten their LEs over 190/190 with overclocking. I haven't heard of anyone trying to wring some serious performance out of the 7200, but I would guess that the overclockability of the memory would be the defining factor.