Translation:The structure is essentially the same.
Is there a rule about when one uses uguale or la stessa? Is it 'equal' versus 'similar'?
The meaning is similar but, grammatically speaking, uguale is an adjective, la stessa is a pronoun (with a definite article):
uguale = alike, identical
la stessa = the same (one), referring to a feminine noun previously mentioned
Lo stesso (only in masculine singular form) can be also used as an adverbial expression:
è lo stesso or fa lo stesso = it's the same ~ it makes no difference ~ it doesn't matter
I understand that in English the adverb are placed anywhere in the sentence. If so, why DL doesn't accept the adverb at the beginning of the sentence? "Essentially, the structure is the same"