No practical difference unless you split hairs. There is nothing like a phonetic alphabet. In fact as enunciated by Gangesh, a language can exist without a script, but a script needs a language to mean anything. So, Roman script as linked to English is far from phenetic system. It is inconsistent. For example the same sound is produced by c and k. So, kauphy is as good a brew as coffee. But not so in Devanagri. There is one and one brew called कौफी. Unlike English, spellings are 100% consistent, provided you prounce correctly. And why chemistry, but char is written as kar!! c, k, ch, ck, qu etc prounce alike. Of course, you don't about Indian languages either. Symbols used in Devanagri are 62. Consonants are 52, Roman has 26 symbols, vowels and consonants included. So how can Roman be used to write Sanskrit, without complicated dicritics? Like it or not, you MUST know all the symbols if you really hope to read Sanskrit from original texts. Pitman created a phonetic system for his short hand system. ith and thee are different sounding. Of course, Gangesh is correct. No script exists without a linkage to a language.