Did British Empire and Thailand exist in the same era?

Yes, the two civilizations both existed around 1782 CE.

Which lasted longer, British Empire or Thailand?

British Empire lasted longer (414 years).

British Empire: Avrupa; Thailand: Asya

British Empire (1583 CE – 1997 CE) and Thailand (1782 CE – present) lived in the same era.

The empire with the most extensive territory in history. It was referred to as "the empire on which the sun never sets."

Kingdom of Thailand · Asia

Did British Empire and Thailand exist in the same era?: Yes, the two civilizations both existed around 1782 CE.
Which lasted longer, British Empire or Thailand?: British Empire lasted longer (414 years).
Which regions did British Empire and Thailand rule?: British Empire: Avrupa; Thailand: Asya