Logic for converting a column values into a CSV record using ISNULL, COALESCE functions

declare @Temp Table(Val int)
declare @CSV varchar(2000)

insert into @Temp values(1)
insert into @Temp values(2)
insert into @Temp values(3)
insert into @Temp values(4)
insert into @Temp values(5)


select @CSV = isnull(@CSV + ',', '') + convert(varchar,val)
from @Temp

select @CSV
set @CSV = NULL

select @CSV = coalesce(@CSV + ',', '') + convert(varchar,val)
from @Temp

select @CSV