What do I have? "Live yeast" or "Sourdough?""

Or are they the same thing?

Hello and thank you in advance for reading and for any help you may offer.  I apologize for not properly introducing myself before jumping in with a problem, but I need advice regarding a "live yeast" culture given me by my Aunt Helen (who is now late) about 12 years ago. At that time she made bread from this yeast at least once a week and had done so for over 50 years.  I spent a few days visiting and she served this bread at every meal, rolls for lunch and dinner, rolls split and toasted at breakfast, and it was absolutely delicious with the most wonderful aroma and a very light open crumb.

Of course, I asked for the recipe and she explained that it was a live yeast and she could give me a start of it, "but you will probably let it die.  Everyone I give it to lets it die."  No pressure.  So Aunt Helen took a frozen cornmeal cake out of her freezer and gave it to me along with a xeroxed sheet of directions and when I got back home I rehydrated it and started making bread and feeding her yeast.  Early on I made a cornmeal cake of the yeast and put it in the freezer because I really, really, didn't want to lose her bread starter.  She was in her upper 80s at the time and who knew how much longer she would be baking.  

My bread was good, but never quite as light or aromatic as Aunt Helen's.  All went well for a while, but it became clear that my husband and I just could not afford to consume this rather rich bread -- made with white flour, sugar and butter --weekly without disastrous consequences to our waistlines and health.  So I made it less often, and tried to remember to feed it (sugar) weekly when we didn't make bread.  Eventually, however, all that was left of my good intentions were two little jars of guilt pushed all the way to the back of the refrigerator.  I tried not to look at them, but couldn't quite bring myself to toss them.  I even kept them when we got a new refrigerator 6 years ago.  Guilt is a powerful thing.  It got worse when she actually passed away last year.  Oh my, I wonder if that frozen yeast cake might be viable?

A few weeks ago I purchased a rye sourdough starter and discovered this wonderful forum while trying to get it going.  Thank you all for the trove of bread making knowledge.  Thanks to information posted here I have produced several loaves of very tasty rye bread and discovered that my dear husband can consume them without adverse health consequences.  Yay!!  Along the way I also learned that there was no real need to purchase a rye starter, but that is water under the bridge.  My next idea is to try making whole grain wheat bread with a sourdough starter.  To that end I thought of feeding wheat flour to the rye starter, but then wondered if it might be possible to revitalize Aunt Helen's yeast instead.

The frozen yeast cake must be at the very back if the freezer, couldn't find it at any rate.  So, I determined to try my luck with those two jars of guilt which had not been fed or opened in 8 or 9 years.  I examined both and selected the most wholesome looking one, set it on the counter and opened it, keeping it at arms length.  A very cautious sniff revealed that it smelled fine.  In fact, it smelled just like it always smelled, maybe just a tad more wine-like.  So, I scraped 10 grams of white stuff out of the bottom, mixed it with 10 grams or water and 10 grams of KA whole wheat flour, stirred and set it in a warmish place.  Within a few hours bubbles appeared.  This morning I fed it again.  Definite bubbles and volume increase and it smells good.  So what's my problem?  

This is not how Aunt Helen fed this yeast.  I am feeding it as I have fed my rye sourdough starter, which I learned here at The Fresh Loaf, with equal parts flour and water.  Aunt Helen fed her starter with sugar.  And her directions are titled "Bread from Live Yeast."  Nothing about sourdough.  Is it a sourdough starter or is it just yeast?  Are they the same thing?  Should I feed it sugar or flour?  

Here are her instructions, in case any of the bread experts here can tell what sort of yeast creature is in this jar sitting next to my modem.

"Bread from Live Yeast"

"To use cake -- put in pint jar with 1 cup water, 1 tablespoon sugar and 3 tablespoons flour.  Let sit at room temperature all day and proceed as with batter."

"To use batter -- remove from ice box early morning and let stand at room temperature all day."

"At night put yeast batter in mixing bowl add 1 pint water and enough flour to make a thin batter, let set overnight."

"Next morning take out 4 tablespoons batter. Put in pint jar with 1 cup water and 1 tablespoon sugar. Keep in ice box tightly covered. Every 8th day add 1 tablespoon sugar if not used."

"Bread -- after removing batter for future use add 3/4 cup melted cooled shortening, 1/2 cup sugar, 2 tablespoons salt and flour to make a dough. Knead, put in bowl and let rise double in size. Then work down by kneading. Put in loaf pans or shape in rolls. Let rise double again and bake."

"To make a cake take 1/2 cup corn meal and work enough batter in it to make a firm cake about the size of a large jar lid, let dry"

I would like to better understand what this is, how to care for it and use it to make bread that we can eat.  It smells good, bready, fruity, a little like a nice white wine. Almost buttery. Whatever it is, it isn't dead, for which I am grateful, and I would like to keep it going for a few more decades.  Is it ok to put it on a diet of whole wheat flour or will it only thrive on white flour and sugar?

Thank you!   Sherry