The following verse (Sanskrit: Sloka) from Srimad Bhagvad-Gita (Chapter 4 - Sloka 13) is most authentic and adequate reference to be quoted
चातुर्वर्ण्यं मया सृष्टं गुणकर्मविभागशः ।
तस्य कर्तारमपि मां विद्ध्यकर्तारमव्ययम् ॥ ४-१३॥
English Transliteration of each syllable with meaning:
chātuḥ-varṇyam — the four categories of occupations;
vibhāgaśhaḥ—according to divisions;
Meaning In English:
The four categories of occupations were created by me according to people’s qualities and activities. Although I am the creator of this system, know me to be the non-doer and eternal.
After quoting above...let me summarize on both of these words (varna and jati)...and their correct interpretation.
Varna - indicative of set of personality traits, and skills and competencies - which also shapes - what would be the ideal role, responsibilities, and possible contribution(s) of an individual as the small unit in the society.
So there are 4 varnas:
Brahmans - Learning, Teaching, propagation of knowledge (either directly acquired or received from earlier generations) in the society, application of intellectual and creative skills for good of individual, and society.
Vaishya - member of business community. Anyone whose purpose of life is mostly focused on creating and acquiring the wealth.
Kshatriya - member of society having great physical and mental capabilities, which are needed to protect the society (to ensure internal and external security of society / state). In English, nearest word to explain this role would be - a warrior or administrator. Therefore, in present context, the Kshtriyas are those who are either into public administration, or in security forces.
Shudra - members of society having one or more technical, professional skills. These skills MUST enable the member to ensure that she / he earns her / his livelihood - by using these earned skil(s).
So what is Jati?
It's an indicative of "what skill set, an individual possess to earn their livelihood to sustain themselves and their family.
Please note that these varnas do NOT have any hierarchy - among themselves. Therefore, I try to company two different varnas - and try to proof or evaluate which is better than other - then basically what I am trying to do is - "to compare an apple with orange"! Which itself is illogical.
And since no varna is higher or lower than other varnas in principle. Last but not least - none of these varna are inferior with other varnas are inferior in ANY WAY.