typesetting parameters

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Hi list,
	I'm having difficulty understanding why one would define a parameter 
with typeset before using it using.  For example:

integer count=1
until something; do
   something else
   something else
   something else
   (( count++ ))
done

I could just do

count=1
until something; do
   something else
   something else
   something else
   (( count++ ))
done

and get the same results, right?  Similarly,  if I define a scalar 
variable or non-associative array with 'var=foo' and 'array=(one two 
three)', is that different from doing 'typeset var=foo' and 'typeset -a 
array; array=(one two three)'?  Any explanations, online guides, or FMs 
to R would be much appreciated.