Please explain the difference and the importance of Laylat Al-Qadr which is in Ramaḍān and the Laylat Al-Barāʿah which people observe on 15 Shaʾbān.
In the Name of Allāh, Most Kind, Most Compassionate
Jazāk Allāh Khayr/ Thank you for your question.
Laylat Al-Qadr (the night of power) is a blessed night found in the last odd ten nights of Ramaḍān.
“The Night of Qadr is better than a thousand months.” (Qurʿān 97:3)
The meaning of this is that the reward of a good deed performed in this blessed night is far greater than the reward of a good deed performed outside this night for one thousand months (i.e. 83 years and 3 months).
On this night Allāh’s Messenger (peace and blessings upon him) has encouraged us to engage in prayer by stating, “Whoever stands (in prayer) during the ‘Night of Qadr’ in the state of belief and anticipation [of Allāh’s reward], all their past sins will be forgiven.” (Bukhārī)
15th Night of Shaʾbān
As far as the 15th Night of Shaʾbān is concerned, some scholars are of the view that, this is a blessed night. One should render additional acts of optional worship and good deeds during this night.
Shaykh Faḍl al Raḥmān Al A’azamī writes;
“An overview of the various narrations regarding this night lends credence to the acceptability of the virtue of this night. The reason being that although these narrations are weak, they are numerous and narrated by a number of Companions. Some are such, that not much criticism has been levied at their chain of narrators. Imam Ibn Ḥibbān has included some of these narrations in his ‘Ṣaḥīḥ” and Ḥāfidh Mundhirī has remarked regarding the chain of some, that the chain is acceptable. Therefore, according to the principle of the professors of ḥadīth (muḥaddithūn), the excellence of the night of Barāʾah (15th of Shaʾbān) is proven from a conjunction of all these narrations. This is the general consensus of the professors of ḥadīth and Islamic jurists, and this is correct. Even Imām Ibn Taymīyyah, a scholar notorious for refuting such things, also accepts the virtue of the night of Barāʾah. He says, ‘So many narrations and reports exist, regarding the excellence of the fifteenth night of Shaʾbān that one is compelled to accept that this night does possess some virtue.’ Some of the pious predecessors used to specially devote this night for ritual prayer. – Faydh Al-Qadīr”
That being said, if someone revers this night and engages in optional worship, it will be praise worthy. However, there is no blame or reprimand for one who may not wish to observe the significance of the 15th of Shaʾbān.
And Allāh Knows Best