पुर्ण भूतकाल vs समान्या भूतकाल

Im not entirely sure when to use what.

To my understanding, its a case of when I did something. 

If I was to say I went to Delhi without a time frame or very recently,   कल मैं दिल्ली गए because it is the recent past or I would say I went to Delhi to buy vegetables मैं दिल्ली गए सज़्बियाँ करीदने के लिए

If I was to say that last year I went to Delhi  पिचले साल मैं दिल्ली गए था as it happened a long time ago. बिस साल पहले मैं दिल्ली गए था

The present perfect would be I have been, to say you have gone somewhere e.g.  मैं दिल्ली गए हूँ
I have been to Delhi.

Am I correct in my understanding?

Hello,

Thats an excellent question actually.

The difference between the two is as follows

पुर्ण भूतकाल = past perfect tense. For example मै आम ख़ा चुक़ी थी  (I had eaten mangoes )

समान्या भूतकाल = simple past tense. For example  मैने आम ख़ाया है  (I ate mangoes)

Let me know if you have any more doubts about this. 

Warm Regards
Adithya Prakash