alone可以作形容詞,但是只做表語,不用做定語.
He was alone in the house.
也可以做副詞.He came alone.是‘獨自’的意思,不含感情色彩
lonely既可以作定語,也可以作表語.
作表語是‘寂寞’、‘孤立’的意思,一般指人孤獨寂寞；作定語指地方荒無人煙,有濃厚的感情色彩
She lives alone ,but she doesn't feel lonely.
She felt lonely when she was left alone.
a lonely place