Give the English meaning of: anu-atma and vibhu-atma. (2.20)

There are two kinds of souls—namely the minute particle soul (aṇu-ātmā) and the Supersoul (the vibhu-ātmā).

In the last part of the purport of Srimad Bhagavad Gita As It Is, Chapter 2, vers 20, Srila Prabhupada writes:

There are two kinds of souls—namely the minute particle soul (aṇu-ātmā) and the Supersoul (the vibhu-ātmā). This is also confirmed in the Kaṭha Upaniṣad in this way:

aṇor aṇīyān mahato mahīyān
ātmāsya jantor nihito guhāyām
tam akratuḥ paśyati vīta-śoko
dhātuḥ prasādān mahimānam ātmanaḥ

(Kaṭha 1.2.20)

"Both the Supersoul [Paramātmā] and the atomic soul [jīvātmā] are situated on the same tree of the body within the same heart of the living being, and only one who has become free from all material desires as well as lamentations can, by the grace of the Supreme, understand the glories of the soul." Kṛṣṇa is the fountainhead of the Supersoul also, as it will be disclosed in the following chapters, and Arjuna is the atomic soul, forgetful of his real nature; therefore he requires to be enlightened by Kṛṣṇa, or by His bona fide representative (the spiritual master).