chownah wrote:I just want to know if there is some practical difference in the three ways to refer to the ball.....to most people there is not.
If a relative clause adds parenthetical, nondefining information, it is nonrestrictive. A nonrestrictive (parenthetical) element is set off by commas.
'the ball, which is red'
When the relative clause limits or restricts the noun or noun substitute (substantive) it modifies, it is restrictive, and it is not set off by commas.
'the ball that is red' / 'the red ball'
this website, source of the above definitions, also wrote: When the relative clause limits or restricts the noun or noun substitute (substantive) it modifies, it is restrictive, and it is not set off by commas.
~My brother that lives in Arizona is named Pat.
In this sentence the clause "that lives in Arizona" is needed to specify which brother, since the reader has no other way of knowing how many brothers the writer has or which brother is being referred to. (One way to think of the issue of restrictive and non-restrictive elements is that a restrictive element provides information that is necessary to narrow the field of candidates down to one.)
But check out this example:
~My other brother, who lives in Texas, is named Sam.
In this sentence the first substantive, the noun phrase "My other brother," conveys the information that the writer has only two brothers, and it also specifies which of those two brothers is being referred to, so the fact that he lives in Texas is extra information--not necessary for specifying which of two brothers is being referred to. In fact, although the brother's name is given in this sentence, the name itself isn't actually needed to narrow the field of candidates to one: the phrase "my other brother" indicates that the writer has only two brothers, and it also specifies which of thoise two brothers he is referring to. (Obviously, the would not say "my other brother" except in a context where he has just referred to the first brother.)
If the relative clause "who lives in Texas" were treated as restrictive, then the sentence would convey the information that the writer has two brothers who live in Texas, and that would only make sense if another brother living in Texas had already been mentioned:
~I have two brothers that live in Texas. One is named Eric. My other brother who lives in Texas is named Sam.
Does this help?