namaste shrI CLN.
As you say, varNa and jAti are different: the terms brAhmaNa, kShatriya, vaishya and shUdra are the names of the four varNas, although the first is used today exclusively to refer to the brahmins caste and the last to all other castes in general, with the third being used commonly with the castes such as the Chetty, Chettiars, etc. The term kShatriya is hardly used, expect perhaps in such caste names as the kShatriya rAju (to which shrI Sathya Sai Baba belongs).
Well, perhaps the largest number of jatis exist amongst the
vaishya varna, because all economic activities come under that from money-lending to agricultural activities. We normally associate
vaishya varna only with trade and money lending, in fact it spans whole range of the economic activities. Brahmins of this age practically have taken many of the vaishya callings. A moneylender/banker, trader, smith, farmer are all vaishyas. It must be remember the specific skills of each trade were taught/transmitted by the seniors and experts within the respective
jatis. There were apparently used to be rigid code-of-conduct for each
jatis -- whether they were documented or not is something I am unaware of.
E.G.:A money lending Chettiar or a mahajan will be ignorant about smithy and vice-versa though both are
vaishyas.
Likewise a temple-priest and a srotriya are brahmins, but there is a world of difference amongst them.
So
jatis approximate trade-guilds though in a much profounder sense.
Contrary to what we imagiine that sudras and panchamas form bulk of the population, it is in the
vaishyas that form the bulk of the populace -- simply because it is for economic activities most number of hands are required.
Although the confrontation between the upper and lower castes today is not because of brahmins, the whole confusion, according to KAnchi ParamAchArya was due to brahmins abandoning their svadharma and women taking up professional employment.
That is not the sole reason according to him. The problem started when brahmin started getting into secular employment (mostly manned by vaishyas or some jatis like
kayastas in north). I am puzzled where
kayastas fit into the scheme of varnashrama.
svadharma of his own brahmin caste is expected to follow it yatA-shakti--to the extent possible for him.
It is easy to say, but very difficult to practice. Just take for instance shaving.
Now it has become a norm to have a shave daily. Many of the old-timers know that many days are excluded for having shave. Is it possible even to observe even a very simple discipline. At best one can do Sandyavandanam before leaving for work and do in evening/night.On tours one may have to give that a miss -- or some people may be determined to do in their hotel rooms in a w/c attached bath.
If one has to talk of keeping a distance from women in menses at workplace, you can well imagine the furore that will be created.