The bond information in the below table is from www.finra.org as of last close on Nov. 9, 2022 (all yields are expressed in annual term):

Select Apple Inc. vs. The Boeing Company Bonds:

Symbol	Callable	Coupon	Maturity	Moody's	S&P	Price	Yield
AAPL4984115	Yes	0.750%	05/11/2023	Aaa	AA+	98.228	4.432%
AAPL4984119	Yes	1.125%	05/11/2025	Aaa	AA+	91.575	4.750%
AAPL4984120	Yes	1.650%	05/11/2030	Aaa	AA+	79.968	4.874%
AAPL4984116	Yes	2.650%	05/11/2050	Aaa	AA+	62.413	5.248%
BA4983333	Yes	4.508%	05/01/2023	Baa2	BBB-	99.720	5.118%
BA4983334	Yes	4.875%	05/01/2025	Baa2	BBB-	97.928	5.788%
BA4983328	Yes	5.150%	05/01/2030	Baa2	BBB-	93.329	6.283%
BA4983330	Yes	5.805%	05/01/2050	Baa2	BBB-	86.404	6.917%

Explain the observed differences in yield. In general, what are callable bonds? What are the differences between investment grade bonds vs. high yield bonds?